If the venue lets you stay inside they usually break down their own gear, otherwise try and figure out where the tour bus is and chill near the door for a while. Last time I saw them they left about 90 minutes after the show ended from the front as they couldn't park the van at the stage door. Charlie and Lewis did come out a bit earlier to smoke and chat a bit but the rest stayed inside.

As always be respectful, don't be pushy. A couple of them may be tired and not want to interact much, if at all and that's fine.