BRITAIN will be staging a Festival of Arts and Culture throughout next year when it celebrates the centenary of the National Trust. A host of events are planned, including a film festival. Some 51 per cent of overseas visitors say they visit Britain for arts and entertainment attractions. BANGKOK will host the 15th annual ASEAN Tourism Forum next January at the Queen Sirikit National Convention Centre. FOR the 11th consecutive year, Amsterdam's Schiphol airport has been proclaimed Europe's best by the British magazine Business Traveller. SAPPORO'S popular Snow Festival will be held from February 6-12. For information, contact Japan National Tourist Organisation, tel Hong Kong 525-5295. THE Himalayan kingdom of Bhutan is revising its visa policy. Until now, the country, which only opened its doors to travellers in the mid-1970s, has allowed visits on either a group or individual basis with a planned itinerary. Because the country does not have the infrastructure to handle large numbers of tourists, the new policy, which will operate from January 1, will no longer allow visits by groups with fewer than four persons. Last year, fewer than 3,000 tourists visited Bhutan, compared with approximately 250,000 for Nepal. TORONTO'S CN Tower has the world's highest revolving restaurant, Top of Toronto, as well as the highest bar, Horizons (1,136 feet). VIRGIN Atlantic is offering HK-London-HK passengers a special $10,000 round-trip Mid Class fare between now and March 31. Passengers must purchase their ticket at least 14 days before departure and start their journey from Hong Kong no later than March 31. WHERE is the United States? You may not believe it, but according to a 1988 Gallup Poll, 24 million Americans could not locate the US on an outline map of the world. And statistics show that young Americans ages 18-24 scored significantly lower than their international counterparts on a test of geographic knowledge.