I went to Wembley Arena last night to watch Prodigy (which was excellent btw). Met at pub called The Torch - if you turn left out of Wembley Park Tube station - Big beer garden.
Be surprised if that was open/accessible though, being so close to Wembley Stadium. It's already got metal barriers installed outside in preparation!
I'm going to be watching from my armchair tomorrow as sadly no chance of getting a ticket! Still, my fridge is well stocked!!!