I'm totally the other way round, whenever I'm in America I love buying Hersheys and all that kind of thing. I guess it's just the novelty factor. Whereas I'm not wild about the chocolate here probably because I can just get it all the time.
Really though buy anything Cadburys. Cadburys chocolate is absolutely lovely, it beats Nestle hands down. I've been on the Cadburys factory tour like 4 times now, so much free chocolate and the smell of the place. <3 Dairy Milk is dreamy, it just melts in your mouth, so nice, definitely try one. In Australia you can get a Cadburys bar called Top Deck - it's dark, milk and white chocolate layered. That's the best bar in the world! Don't think it's available at Disney though.