Anything salty goes with beer. Mixed nuts, pretzels, etc etc, and they also make people thirsty, which can only be good for business. Chocolate goes good with certain liquors (I know I like it with whiskey), but if you plan on selling actual food in a pub, things like garlic fries, chicken wings, potato skins and other finger foods are quite popular in the States. It should obviously be catered to wherever you're doing it, so why not check out some local spots that seem to have large crowds? If people are eating there, see what they're eating.