AME, I wouldn't let such concerns bother you. There are plenty of basic PPLs who attend the event. It was the best flying day out I've had since I got my license a couple of years ago and I'd recommend it to anyone. I've stayed in touch with the 2 chaps I flew down, and we've been up a couple of times since then. I'll certainly be back in 2009.
The only skills you'll need are 1) quick and accurate on the radio, and 2) nice and slick in the landing and vacation; purely due to the volume of traffic. I believe the landing rate at Old Warden this year was higher than a Heathrow rush hour.
PS. Plenty of time to get an IMC rating done before PP comes around
