I think Dublin would be too much in that amount of time. You would have to fly (very cheap and lots of flights from all four airports) and then fiddle around with different currencies etc. Much better to stay in England and fit in a quick trip to Oxford or Cambridge or, if you prefer ecclesiastical architecture, Salisbury - all easily reachable by train in an hour or so.
You really need to figure out what sort of culinary experiences you are looking for. Is it diverse food you won't get at home, is it Michelin starred stuff, is it good food in a trendy atmosphere, is it cutting edge British farm to table? I could go on but the food scene is huge and, without proper research it's easy just to end up in tourist traps, of which there are also plenty.