My choice of route from Calais would be to Boulogne; Abbeville; Rouen; Le Mans; Anger and Cholet. You'll pay around 10E from Boulogne to Abbeville, although you could use the N1. Abbeville to Rouen is toll-free motorway. From Rouen to Le Mans you could use the A28 but the tolls are high. The D438 (N138) runs fairly close to it if you don't fancy the tolls. Again the section from Le Mans to Anger can be done on Autoroute but you could use the D323 - it used to be the N23.
You've got to weigh it up. Spend less time driving and spend more on tolls, or take more time and see the towns and villages.