Reliably on this British import, we’re treated to a few celebrities not often seen on talk shows, a U.K. pop-culture institution, and one homegrown celebrity that hasn’t registered at all in the States. But on Graham Norton, they all share the same couch, and the same air time, and the loose democratic format is a delightful way to get to know them all. Tonight’s couchmates include a couple of Sirs: composer Andrew Lloyd-Webber and pre-Beatles British rocker Cliff Richard. Oh,