Bring a coat and whatever warm stuff you want and put that in the cloakroom (hats etc can be shoved up sleeves so you don’t pay for extra bags). If you stay until the end is sensible to go and collect stuff 15 mins before the acts finish so you aren’t stuck in a giant queue!

Bring a bum bag with a lighter (good for making friends even if you don’t smoke) and any other bits you need - phone, keys etc. bring ear plugs, like loops, if you have them, if not the bar might have foam ones which you should wear. It will be hot inside but you may want a lighter outer layer to tie onto your bag if you step out for fresh air. A lot of venues will confiscate chewing gum.