Where are people drinking before the game? This site suggests that the Great Northern might be worth checking out (and it's close to the ground). It has guest ales, but doesn't look like it does much in the way of tucker.
i've been there before. it was a basic football boozer. post-match, so we weren't looking for food. the ale was okay, but nothing to write home (or on rageonline) about. big sky sports screen, full of oxford fans.