Thanks to Chris Mills on Twitter, I now know that you can find it by logging in here. It would be much handier if this was also included in the confirmation e-mails, though.
I just thought I'd pass on the information in case you were in the same situation and don't indulge in these social networking thingies.
If my pass doesn't arrive tomorrow, they will reprint it - but I'm worried I'll have to pick it up in Birmingham. I was kind of relying on Anna to do the origami for me.