got the name of the campsite totally wrong its..Beausejour

Hello All
First timer to CA and after 15 years of saying I'm going to Le Mans, this year tickets and site are booked.  Just need some advice on the return ferry.  Whats it like getting away after the race ?  Had to book the Bassecar campsite.    Have decided to do the calais route and we are using a friends camper van, so max speed will be 60-70.  
I have decided to book the ferry early morning on Thursday so we can get to the site late afternoon Thurs, is this adviseable or could we leave it until Friday afternoon to arrive.  Any advice appreciated.

Rick