Honfleur, a huge Aire with hook up points, by a mega yacht basin and just so much fun. Eminently reachable on day one, an easy drive from the tunnel.
Bayeux, park up in the market square, the tapestry is amazing, the town is amazing, the food is amazing.
The beaches are a must. Provincial camp site at oustreham, a short walk from pegasus Bridge. The campsite is a bit dismal, although it was a dark, wet and windy October night when I was there, but brilliant for Sword and Juno and Pegasus bridge museum is a must.
A couple of campsites around omaha beach, the American museum is good, the American Cemetery poignant and evocative. Unfortunately the thousands of American visitors also make it one of the most expensive places in Normandie.
Do go to port en bessin, not for the pretty harbour and overpriced restaurants but for the walk up to the point where 47 Commando fought one of the most spectacular actions of the D Day landings. Read up on one of the many stories about operation Aubrey, then follow the path taken by Captain Cousins. Undoubtedly he deserved a posthumous VC and why he never got it remains a mystery.
You can go to Rouen. Good luck. The place is a nightmare. I only went to look at the Cathedral and to follow the trail of William of Normandie, I wished that I hadn't bothered!