Regarding food, it's so individual, and it's really hard to know what you fancy at 3am. I took plenty of crappy things like potnoodle and tins of heinz spag bol, as well as a thing of cherry tomatoes, and quite a few different sandwiches.
I swear though, the best tasting thing ever in the whole world was the jacket potato with veggie chilli I had from Wilfs at about 2 or 3am.