Relax and get on with it. Did OASC about 6 months ago, and while Part 1 is damn stressfull, you should be well prepped for it by the time you go, and Part 2 is just good fun.
'Enjoy' it! (as much as you can at the Hotal Cranditz)
P.S. Only major point about the FAA I saw when applying to the RAF: do you really want to spend that much of your life at sea? <img src="confused.gif" border="0">