H, it might not be Bonfire Night yet, but the bloody Christmas stuff is in the shops. Get the bookings done and paid for before the Xmas hit on the bank balance my man!
I used to do the Portsmouth-Caen route every year, overnight out in the week and back on the Sunday night boat, when the extra cost was about the same as the additional fuel used by going via Dover. Gave up on the route about 5 years ago because it was getting so pricey and the difference had risen from around £100 to around £200, and now is £3-400. That is a lot of beer or, indeed, an overnight stop in a hotel on the way out, back or both.
And don't worry about boredom on the autoroutes. The section from Calais/Boulogne to Rouen (2 hours or so) is pleasant enough with some good rolling scenery (and it's cheap - I think that the toll for that comes to about 7 euros), and the run from Rouen to Le Mans is the most boring stretch imaginable. So on the way out, I head from Rouen down the old route to Alencon and Le Mans, and only use the new autotroute from Le Mans to Rouen coming back.
I do miss the old route - the proximity to Le Mans, the atmosphere, the convenience of the overnight cabin, stopping at Falaise for coffee etc etc.. But Dover Calais/Boulogne has plenty going for it too aside from price - Rouen is not a problem once you've found the back way way through it, the Baie de La Somme stop is delightful, and there are plenty of places to stop off enroute with hotels or campsites if you want to break the journey up. And you can still drive the bit of the old N138 that remains atmospheric - between Le Mans and Alencon.
MG Mark
