LOVE IN A COLD CLIMATE (304 pp.]Nancy MitfordRandom House($2.75).
British Nancy Mitford's bestselling Pursuit of Love, published three years ago, especially pleased two groups of U.S. readers: 1) heartthrob hunters who panted with pleasure over Pursuit's hot Paris romance; 2) determined esthetes who gleefully bang their teacups whenever the sharp, wry tongue of their cult leader, Evelyn Waugh, wags through a new writer's prose. Group One will shiver in dry-eyed disappointment over Love in a Cold Climate, Miss Mitford's hot-weather novel for 1949. Group Two will fare betterif they can take their Waugh...