LONDON

One of the essentials of a good trip abroad is finding the right accommodations at the right price. London, perhaps more than some other European capitals, can be expensive without being a good value. But dotted among the mediocre are some hotels and serviced apartments that will satisfy the most discerning. The following selection is a highly personal one; all the listings have a particularly British flavor and distinctive personality. For simplicity's sake, the accommodations have been divided into top, medium, and lower-price groups, ranging from the very posh to the simplest bed and breakfast.

Starting at the top, there is the Connaught Hotel at Carlos Place, Mayfair W. 1 (telephone 499-7070). This splendid establishment, built in 1892, is the last word in civilized comfort. The smallest of London's very grand hotels, with 90 rooms and 24 apartments, it is run along the lines of a very well-organized country house, with exceptionally high standards of service. Its atmosphere is that of a discreet gentleman's club. It is a favorite haunt of publicity-shy celebrities, diplomats, and businessmen, who nonetheless enjoy being waited on hand and foot by an army of gentleman staff in morning coats. A carved-mahogany staircase leads up to the spacious, comfortable bedrooms, most of them with open fireplaces and many furnished with magnificent antiques. Rates at the Connaught start at $80 a night for a single, $125 for a double, and $245 for a suite. In keeping with its respect for the values of another age, the Connaught has no telex. The management prefers guests to book in writing.

Claridge's, in Brook Street W.1. (telephone 629-8860, telex, 21872), a hundred yards from Bond Street and the American Embassy in Grosvenor Square, barely needs an introduction, but positively demands a mention. It is perhaps the best example in London of a harmonious blend of the dignity of the last century with the comfort and convenience of today. All of its 205 rooms are individually furnished, and some of the suites even boast grand pianos. Single rooms start at $106 a night, doubles at $144, and suites at $250, including service charge and value-added tax. If you cannot afford to stay at Claridge's, you can still pop in for a taste of splendor at a knockdown price in the small Causerie Restaurant. Set lunches are from $11.50.

Among the better hotels in the medium range is the Goring, 15 Beeston Place, Grosvenor Gardens, S.W.1. (telephone 834-8211, telex 919166). This fine, 100-bed hotel, built in 1910, is still run by the Goring family. It has preserved its old-fashioned charm while offering a high standard of accommodations. Although it is situated in the heart of town, behind Buckingham Palace and close to Victoria Station, the Goring is an oasis of calm. Its decor is traditional, with a comfortable lounge overlooking a pretty garden. The bedrooms are stylish, with modern bathrooms, televisions, and hair dryers. Single rooms cost from $76 a day , doubles from $99. But if you are planning to visit London in August, the Goring has a special offer. Provided you stay for at least one week, the daily rate drops to $42 a person a day, including breakfast.

The Alexander Hotel, 9 Sumner Place, S.W.7 (telephone 581-1951/5, telex 917133), is a real find. It is a distinctive, elegant little hotel, close to Hyde Park, Harrods, the museums, and some of London's best restaurants in the medium-price range. South Kensington tube station, with its direct link to Heathrow, is just 200 yards away. With its graceful, white 19th-century facade, high standards of service, and impeccably decorated and maintained rooms, it offers a welcoming home away from home at a reasonable cost. Most of its 36 bedrooms (which range from small singles to a suite that will accommodate five in comfort) have their own showers or baths, color televisions, and direct-dial telephones. Breakfast is served in a pine-furnished dining room that opens onto a small garden. In summer, when it is ablaze with color, afternoon teas are served here. Pre-theater buffet suppers are also available for about $9. Single rooms start at $30; twin-bed rooms at $46, including a generous English breakfast, tax, and service.

For those who prefer the freedom of their own front-door key, the owners of the Alexander also offer serviced apartments in nearby Clifton Lodge, 45 Egerton Gardens, Knightsbridge, S.W.1 (telephone 584-0099, telex 917133). The prices are dramatically cheaper than at most hotels offering similar accommodations. Studios for one or two people cost from $41 a night; two-room apartments for three or four people range from $58 to $73 a night, excluding government tax. An advance deposit of $304 is required. Clifton Lodge is a modernized 19th-century house, with its own elevator and central heating. All the apartments are roomy and modern, with their own bathroom, fully equipped kitchenette, and private telephone line. There is a resident manager, full housemaid service, and 24-hour valet service.

Another London base that combines the freedom of Clifton Lodge with a wide range of facilities is the Dolphin Square Apartments, Dolphin Square, S.W.1 (telephone 834-9134). One of the largest apartment blocks in Europe, it is within easy reach of Victoria Station and the West End. Dolphin Square has its own swimming pool, sauna, tennis and squash courts, garage, and launderette, as well as a shopping arcade with a supermarket that stocks American favorites. If you do not feel like cooking, there is also a restaurant and French brasserie overlooking the swimming pool. Prices range from $50 a night, or $301 a week, for a one-room apartment with a single bed to $152 a night, or $900 a week, for a four-room apartment that can accommodate up to six. Towels are changed daily, sheets twice a week, and each apartment has its own stock of table and bed linen. Kitchens are well equipped and bathrooms adequate. There is no deposit, but one week's rent is to be paid in advance.

The Colonnade Hotel is at 2 Warrington Crescent, W.9 (telephone 286-1052, telex 298930). This Victorian hotel, although slightly off the beaten track, is within a few minutes' tube ride from the center of town. Each of the 52 high-ceilinged rooms is decorated in a different style, and sometimes a mixture of several. All rooms have a television, hair dryers, and trouser presses, and most have private bathrooms. Some double rooms boast four-poster beds; one even has a sunken bath. There is a small garden and a dining room, where breakfast is served. Dinner is also available. Prices, including breakfast, are from $28 for a single, $43 for a double.

Two of the best-value bed-and-breakfast places in London are within a hundred yards of each other, near Baker Street Station, just a stone's throw from Regent's Park and Oxford Street. Milford House Hotel, 31 York Street, W.1. (telephone 935-1935), has six rooms: four doubles and two singles. It is a Georgian terraced house with bright, immaculate rooms, plenty of cupboard space, and comfortable beds. There is no lounge, but there is a breakfast room. The two public bathrooms are spick-and-span. Milford House is run by a formidable Scotswoman, known to one and all as Ronnie. She thinks little of waking at 5:30 a.m. to cook breakfast for guests who have an early plane to catch. If it's a friendly, homely atmosphere you are looking for, Milford House is for you. Single rooms with English breakfast are from $15 a night, twin-bed rooms from $ 21 a night.

Merryfield House, 42 York Street, W.1. (telephone 935-8326), is a neat, flat-front town house with cheery window boxes. It is small, with seven double bedrooms, all with modern bathrooms and a pretty color scheme. There is a radio in each room and televisions are available on request. The manager, Bridget O'Brien, ensures that everything runs like clockwork and that the place is spotless. The cost of a double, including full English breakfast, is $33.

The following suggestions are just a handful of the burgeoning number of good London restaurants. They include something to suit every pocket and palate.

For the gourmand visiting London, one of the first ports of call these days is Tante Claire, at 68 Royal Hospital Road, S.W.3. (telephone 352-6045). It's presided over by a highly inventive chef, Pierre Koffmann, with French cooking. Set lunch is $16; a la carte, about $84 for two. In much the same class, and even harder on the pocket, is the renowned Roux brothers' Le Gavroche, 43 Upper Brook Street, W.1 (telephone 408-0881). Cooking is French, with the emphasis on nouvelle cuisine. For such specialties as mousseline de homardm, expect to pay about $106 for two a la carte. Set lunch is $30.

In a slightly more modest price category, the English Garden, 3 Lincoln Street, Chelsea, S.W.3. (telephone 584-7272), is a charming restaurant inside a white-front town house. Some of the tables are in a glass-top conservatory in the garden - hence the name. The cooking is a fine example of traditional English, with such dishes as scrambled egg and salmon, beef Wellington, and an upmarket version of bangers and mash (fried sausages and buttered mashed potatoes). It's about $53 for two, a la carte.

But there are also plenty of fine restaurants where you can eat cheaply. The Last Days of the Raj, Drury Lane, W.C.2 (telephone 836-1628), serves Indian food - some mild, some highly spiced. Excellent breads and tandooris. Set lunch and dinner are from $10; a la carte is about $27 for two.

There is a good atmosphere at San Frediano, 62 Fulham Road, S.W.3. (telephone 584-8375). It offers Italian food with homemade pasta. One of the house specialties is crepes stuffed with ricotta and spinach. A la carte is about $30 for two.

Finally, if you're shopping in the revamped Covent Garden, positively bursting with boutiques and restaurants, and just want something quick and simple, try ''Green and Pleasant'' at 111 Long Acre, W.C.2., opposite Covent Garden tube station. It is self-service, open seven days a week from 10 a.m. till late, and has a vast choice of salads, quiches, and gooey cakes. You will be quite full for about $5.

Note: Prices were converted from pounds to dollars using an exchange rate of 1.52 dollars to the pound.m