When it comes to eating I have no specific recommendations. All I can say is try a bit of all the local cuisine.
Go to a different corner restaurant every evening. Stop in a pub and take in the atmosphere. Stop by a SubWay, yes the sub-sandwich shop. Why? We have those in America. Yes, but being in Europe they have different selections that must be seen.
Also, you should pick up a selection of your favorite snacks and candy bars and compare the taste to what you're used to. You'd be surprised at the difference in taste between an American candy bar and its British cousin. I'm not talking about a British version, I mean a Snickers from the States tastes different from a Snickers in Britain.
The point is, immerse yourself in the culture and try something new and different. Also a warning, carbonated water is popular in England, so if you want normal water be sure to specify.
