We went last year and camped in the yellow campsite (which is the FC Stern ground), a bit basic but OK. The campsites next to the circuit don't sleep!! We are going again at the end of our French 2 week tour.
I want to be next to the circuit then! It looked like £400-500 for the van for 4 nights when I was looking. Do you mind me asking what you paid?
I'll ask the better half for the exact amount as she booked it. But think the camping was about £100 for the 4 nights. General admission was below £100 each. We stayed til the Monday last year so we could have a drink on the circuit.