The best route out, clear for the last three years, is West down the lane between the Blue parking and camp. It takes you to the top ie North part of Arnage Village from where you turn right and end up on the Le mans by pass. We saw no traffic at all having left the race post finish but not waiting for all of the podium stuff.
As to the more general route we headed toward Granville and took the N road to Cherbourg, fewer Gendarmes and no tolls.
Best of British.
Doug