Went from the main entrance to Arnage last year during Thursday practice. A shuttle bus was not available, I was told this is only running on Saturday/Sunday (Does someone know the schedule?). Started walking, ended up hitch-hiking after a while, worked great, a french delivery van gave us a ride. Even scored a ride back with a nice british bloke in a 1950 (?) open top Bentley when hitch-hiking from Arnage back to the main entrance.
Hopefully the bus schedules will be available in 10 days' time.