As others have said, MetalMarc, it's not an examination for us people bringing stuff to sin. Most creators are happy to break up the monotony of a signing with a little chat with the peeps thrusting comics under their noses, but at the same time they are probably just as happy to do a few quick ones without chat just to keep the line moving.
I know these events can be tricky with social anxiety but see how you get on, no-one is going to test you on your Dredd knowledge. Hopefull your first event will go well and maybe at the next one you might strike up a converstaion with your neigbours in the queue. Some of the best conversations I've had at conventions have beewn with people I don't know in the queues.
As for speaking to the creators just start by telling them you love heir work, and that it's good of them to do the signing. That sort of stuff is currency both for the creators and for all the organisers who go to such lengths to arrange these events.
Go, get some books signed, have fun, come back for the next one and say hello. The 2000AD crowd is a friendly and welcoming one.