Don't panic.

As was said before, you just have to take the confirmation (with the confirmation code on it) and the card you used to book the tickets with (this is very important) with you on the day, and you can pick them up from the ticket office.

If you used someone else's card to book the tickets, take a photocopy of the card (both sides) and get them to write and sign a letter saying they've bought the tickets but they're your tickets. You don't necessarily need this, but it's always best to make sure!

The ticket office opens at 6pm.