Whats the deal with wristbands at these?

I'm seeing HEALTH later, who are suposed to be on at 7-730 or something, so i'm planning on showing up at around 6. The question is: can you show up, grab a wristband, then fuck off and come back in an hour to get in and see the band, or do you have to turn up early and stand in a queue for an hour before getting a wristband and going straight in?

Basically i'm trying to work out whether i need to eat before i get there, or if i can go get something after getting a wristband.

THANKS PEEPS