IIRC Pizza Hut have ben doing that for years, and the prices on the top part of the bill are lower than the prices on the menu, because they just add the VAT on at the very end. Certainly I've never been taken by surprise by the VAT line, but then I do read menus in resturants pretty carefully for dietary reasons, and the first time I went to one of those I loudly pointed out that they were trying to swizz their customers to the people I was with.

It's probably very useful for people who can claim expenses from VAT registered firms for the meal out. But I do get driven spare by the way that Staples catalogues and suchlike are all ex-VAT, I get fed up of doing "and about another fifth" on every figure I read.