When you collect your camping ticket and have stuck it to the windscreen. You can go in and out of the camping . car park anytime you wish.
My advise is that if you are having tickets sent to your home, go direct to Beausejour, find a spot , set up , then go exploring .
I was in BSR last year and the coming and going was no problem except on the Sunday after the race. The roads were a little full.
** Just realised you are arriving on Monday ** Take your time, No hurry.
You may even want to try the ACO offices to try and change your tickets, could be a good time to try .
Route to BSR. - When you get into Le Mans from any of your chosen routes, follow the signs to BLUE camping . When you get to the circuit follow the road along past the standds , and the Blue / White Parking areas. Keep on that road until a roundabout , wherer you turn left , go under the track ( perminant road bridge ) and BSR is on your right.
Enjoy.