A tempting preview of the Edwardian trimmings and fare at the clubby Bentinck Hotel, Duke Street, London, S.W., where ""Duchess"" Louisa Trotter will preside on public TV this fall--courtesy of amanuensis Michael Smith, the British chef responsible for the authentic cuisine and split-second ""culinary choreography."" He'll have you watching for the debut of Louisa's ""Love Swan,"" an ice-cream confection--ringed by blazing cherries--shot at length in a 100Â° studio; she'll prepare you for the elaborate table settings and elegant manners (""knowing what to pick up with what""). Then come savory breakfasts, wheeled in on special tables; hearty soups, like English Pea and Danish Cauliflower (in preference to the ""less interesting"" French versions); ""My Famous Pies,"" a chicken, veal, and ham pastry mass-produced to pay off a domestic debt (see Michael Smith on the logistics). TO say nothing of King Edward's Grouse and other game dishes; proper Victorian Cucumber Sandwiches for afternoon tea; A Good Madeira Cake; Isabella Beeton's Syllabub, and other basic British sweets. With precise instructions, glossaries of British and American terms, and a garnish of tart observations.