At risk of pissing of Plax... My order seem to have arrived less then a hour ago and was accepted by my neighbour. Total delivery time was 4 days from the moment of ordering to receiving the order.
I think I can get you a guest pass Plax, if you still need one. My collectors edition has 3 of them and I wanted to save 2 for colleagues at work.
Perhaps if you order now at amazon.com you can have your package saturday already. Then again, you still wanted to give amazon.co.uk till tomorrow right?
I really hope your order arrived already, if not then we'll find a solution for you so you can keep playing.
[edit]
Colleague at work just told me as well that the english mailing system is notorious for their incredibly slow delivery times and take over 2 weeks for orders to get through.
For everybody else here,
never order any games from the UK if you plan to play on headstart or release day, unless it's a digital copy of that game.