Have a good run at Pendine, I'd love to pop down, but I don't think I'll have the time this year.
I'm not sure how driving in France will prepare you for driving in the UK, aside from the obvious driving on the other side of the road, and the car being a mirror image (apart from the pedals which remain the same) the main gotcha is priority at round abouts/traffic islands, or whatever you want to call them, in France the driver entering the round about has priority, in the UK the driver on the round about has it. You might still come across priority to the right junctions in France where the farmer pulls right out in front of you on a main road, we have none of that nonsense in the UK (well, not legally anyway).
You'll be back to mph in the UK, fuel is still in Litres, which is probably easier for you as our gallons are bigger than yours, so MPG can be confusing.
No idea where else in the UK you might be heading, but transport museum wise, National Motor Museum Beaulieu (pronounced bew-lee), and the National Motorcycle Museum nr Birmingham are probably the main ones, The Heritage Motor Museum isn't that far from the motorcycle museum and is all British cars.
Andy