Is this realistic? --- London to Normandy to Nice

Provence to Nice by car is the time consuming part. Maybe fly?

Sure, why not? As long as you have enough time.

Double check that your ferry takes pedestrians, a few don't. It's probably remote from London. It might beat changing rail stations in Paris, however. I personally think Normandy pairs poorly with England. I also found that Northwest Spain also pairs poorly with England, despite physical proximity. But there is tremendous demand from Americans for England and Normandy. Can you delay this for another trip? We flew into Paris, TGV to St. Pierre des Corps, car rental for Loire, Brittany, Normandy, and back to Paris (clockwise circle, two weeks). Since we'd already been to Giverny, that obvious stop wasn't needed.

You might think about what you want to see between Bordeaux and Provence. I'd find that drive tedious, and not much more attractive than a U.S. interstate, I'll bet. The nice towns seem always to be 30 minutes off the highway. We once took a TGV to Avignon and rented a car there.

Edit: Even within Normandy and Brittany, the stops were always a trek from the highway, like Dinan, Vitré, Coutances. Sometimes those spur drives were scenic. Although we slept right outside Bayeux, the high demand for D-Day Beach touring means heavy traffic and crowded parking lots. What month is your trip?

I'm always concerned when someone mentions taking a ferry from England to Normandy. I've twice planned to do that crossing with a stop or two in the Channel Islands. Two of my five ferries were canceled, one of them for three days. One trip was May/June; the other was July/August. No one else has reported such disastrous luck, but a ferry cancellation would really mess up a short trip.

I too experienced a ferry cancellation. In our case we had to drive like mad to a different ferry port to catch the only boat going across that day. If you are spending your England time in London, getting from London to Portsmouth will eat up a certain amount of time and then in case of a ferry cancellation (unlikely, but could happen!) what will your fallback plan be?

If you have no plans to tour around southern England, I'd recommend booking Eurostar London to Calais. Get a rental car in Calais and head off to Normandy. https://www.eurostar.com/uk-en/train/france/calais

Thanks all! Sounds like flying to Paris and starting there to go up north may be the way to go... back to Paris and then then a train to Avignon where we can pick up a car, drive through Provence (which I have already done) and fly home from Nice.