check out SpeedChills.com
have camped in most sites over the years, and now always opt for Beausejour .
Simply because it's not such a bad location as some would have you believe and Speedchills is adjacent to where we camp, and they provide shelter, cold beer, tea/coffee, good food all day from breakfast to dinner, big screen tv, live bands, clean toilets etc all for £20. Most important of all in my opinion is the shelter. LM in last few years has been sweltering, but when it rains, it really does and can make life very miserable. So having the shelter is a win win.
as a campsite, it's less rowdy than others, is tree lined, adjacent to the Porsche curves and woodland which backs onto the track (ideal for qualifying viewing).