Hi Jem,
Good to see you back.
It's auto route most of the way, except you still have to go through Rouen, no new bridge yet.
3 sections, 1st from Tunnel to Abbeville, toll about 7€.
Abbeville to Rouen, free.
Rouen to Le Mans, about 16€.
That's each way.
Time, under 4 hours if you don't have holdups, cruising on the speed limit.
Forget Paris, longer and probably more expensive.
See you there.