Phil,
Happy for you that you sold the 456, it can't have been easy to see her go, but she sounds to have gone to a good home. So you have decided to keep the 4200, or is it still on the market? I would be inclined to hang on to it, as you know the car and how good it is. Driving in Europe in a RHD is not really an issue, lot's of us have done it and you can as previously said get a toll pass if you need to.
Happy Days in Normandy mate, don't be a stranger though..!!
Cheers
R