Lorry,
from the Houx entrance, walk into teh campsite and head to the permanent Shower and WC block, from there there is a back gate where you can walk through and follow the fence line on your right to the Bugatti bridge. This talks you to the carpark next to the visitor medical centre and the back of the paddock. Alternatively, from the entrance to houx and houx annex, follow the service road from Chem aux Bouefs towards the Bugatti, Turn left and follow the tarmac road with the backing on your right to the bridge and cross.
PM me and I will send a map you you:)