Guide for British theater buffs: good reading, too; London Theatre Today, a Guide for Travelers, by Mildred and Al Fischer. Phoenix , Ariz.: Golden West Publishers. $4.50 (paperback).

For the visitor to England, theatergoing and London are almost synonymous terms. Attending plays in the British capital offers civil amenities, some of the best acting in the world, and ticket prices that are still affordable despite inflation. With all of this and more in mind, Mildred and Al Fischer, a couple of Arizona theater buffs, have put together "London Theatre Today," a yellow-covered paperback filled with facts and helpful advice about the theater scene in London and beyond.

After a brief backward look at centuries gone by, "London Theatre Today" gets briskly down to such practical matters as buying tickets, locating theaters, arriving on time (curtain times vary), and the facilities for food and drink that make British playhouses so hospitable.

The book's main section describes and pictures the more than 30 West End theaters as well as those on the South Bank and in Central and Outer London. It also provides a sample listing of the more than 150 offbeat theaters (alternative, club, fringe, pub, school) that dot the theatrical landscape. The authors conscientiously list addresses, phone numbers, bus and underground (subway) routes. Principal theater institutions, bookshops, and helpful publications are mentioned. There are also several maps and an index.

Mildred Fischer, who wrote the text, presents the fruits of the Fischers' research and experience in a pleasantly informal style that communicates the couple's own enthusiasm. (The book could be an agreeable way to pass some in-flight time.) The guide informs the reader, for instance, that the storied Drury Lane Theatre (1812) is the oldest West End theater still operating; that the fabled Palladium, the greatest of British music halls, is the largest, with more than 2,300 seats; and that although the Savoy (1881) has long since surrendered to other entertainments, it remains a monument to Gilbert and Sullivan and Richard D'Oyly Carte.

"London Theatre Today" pays due attention to Britain's great institutional theaters -- the Old Vic, the National and its imposing new home, and the Royal Shakespeare company in London and at Stratford-Upon-Avon.Two pages provide descriptions and photos of the rising Barbican Centre for Arts and Conferences, whose structures will include the RSC's new London quarters, a 2,000-seat concert and conference hall, a studio theater, three movie houses, an art gallery, and a lending library. It's due to open in early 1982 (months later than the date given the Fischers).

The specifics reported in the book's 245 pages confirm a number of impressions about the British theater. One of these impressions is the longstanding Anglo-American connection which has so enriched the theater on both sides of the Atlantic. Another is the amount of theater renovation, rebuilding, and even new building that has gone on in London and beyond in recent decades. As Mrs. Fischer writes of Sadler's Wells (which actually has a well), "The drama onstage . . . is matched by the drama of the theater's history."

(If your bookstore does not have "London Theatre Today," it is available by mail direct from Golden West Publishers, 4113 North Longview, Phoenix, Ariz. 85014 for $5 postpaid.)

A theatrical guide available in England is "theatre London," compiled by the British Centre of the International Theatre Institute and published by London Transport. It covers more than 200 playhouses in the London area and gives booking information, facilities, policy, and historical perspective for each theater. The paperback guide tells how to find out what's playing and how to get to the theaters by bus and underground (with a detailed map section). "Theatre London" is obtainable for L2.95 from the British Center of ITI, 31 Shelton Street, London WC2H 9HT.