The Royal Ballet and Opera’s new restuarant should be a destination, whether or not Tristan und Isolde whets your appetite Smart Italian restaurants in cultural destinations are like buses: you wait ages for one and suddenly two come along at once. I recently praised Locatelli at London’s National Gallery. Returning to the city, it is the turn of Cicoria at the Royal Ballet and Opera, Covent Garden; a joint under the aegis of Angela Hartnett, well-known for her upscale restaurant Murano in