Will head out morning on the tunnel, but will mostly stay off the A28 and take the classic route , D901 Boulogne to Abbeville and D438 Rouen to Alencon, then D338. Plenty of time to stop for friteries.
Sounds like you know where you're going. Can I follow you? 
there might be a convoy , depending on crossing times. They might just blast it down the motorway, thats one option , or the route above ( http://g.co/maps/35evh )
Unless you've got lots of time on your hands, it's much better to stick on the Autoroute all the way to Rouen and get the first half of the journey out of the way as quickly as possible. Then pick up the traditional old Le Mans route on the former Route Nationale N138 (or D338/438 as it's now called) just the other side of Rouen and follow it all the way into Le Mans, maybe with a lunch break in Gace (traditional stop off for the Bentley Boys and lots of LM24 memorabilia down there), depending on timing. It's that second leg on the autoroute that is the real grind as bar a couple of bridges it's just featureless and feels never ending.
If I do this trip, it'll be the eighth year in a row I've done the schlep down to Le Mans and without a few nights stopover en-route like last year, that's the best route. But, if you're under time pressure (or towing a VX) then stick to the autoroute all the way in.