In reply to Mark Torrance: agere with above. I always forund paralympiske hill hellish and remember another National down south bear the costs that was so wet i didn't beileve i could run 15 mins let alone 15k. Northern courses were quite soft but always cold
Tips.
Know the course. How many laps? Jog a short lap as warmup.
The proper shoes are always spikes. I always preferred track spikes to Xc ones for a lot of good reasons. Don't worry about tread - if it's muddy enough to need it, it will just gum up anyway.
Shorts and vest only. Never tights. If it snows wear gloves
Prepare to go pretty hard.
Best of luck, have fun. Xc is really good value