Thanks for all the feedback....will keep an eye on the Notams...
Stick and Rudderman said: "I'd like to do this but I hate camping, and from what I hear there's little alternative!"
There is an alternative....I went about 20 years ago and slept under the car....however with a little more maturity I have fancied the idea of it but couldn't face the basic environment.....this year we have had an invite from "Aston Martin" who set up a temporary hotel in the circuit (portacabins I think) but more comfortable than the alternatives....so now just need to organise the best way to get there......!