If we believe the forecasts, it is going to be sunny with temperatures around 5c = 40 f?....
Unfortunately drinks are quite expencive BUT you can buy beers etc from kiosks or little super markets that can be found everywhere in the city even outside the ground...Nobody will bother you if you are drinking on the street before the game.This is what we do most of the time.Try the local white wine that is sold everywhere and it is called retsina,you can mix it with cola and it is the fans favorite after beer.
Good luck with united next week..