There are plenty of sites (non-bookable) around Francorchamps. Avoid the one behind the hotel, as they will rip you off, good and proper! But there are no proper facilities in many of them - however, they are cheap and cheerful. We will certainly be going back to our favourite one for the 24 hours, which is on the hill above the main entrance - at night we could see about 6 different bits of the circuit from there. But it is very basic - though at 8 euros a night, who's complaining?
Termie
Can you really just turn up and get on one of these sites? I'd need somwhere that had a wateer tap, and somwhere to drain the chemical toilet.
cheers
Gib