You'll just as easily find roundabouts in France as you will in the UK, though they'll be driving the opposite direction.

Rule of thumb: Anyone in the roundabout has right of way over anyone wanting to enter it. Once you're in the roundabout, you have right of way over anyone trying to enter.

I've driven right-hand drive cars in Australia and the UK. I've never had a problem making an adjustment, save a few sheepish moments when I tried to enter from the wrong side of the vehicle, or reached to the incorrect side looking for the seatbelt.