In reply to Rock to Fakey:
You would basically have to become a 16-17 French learner driver (different rules for 18+). You probably need a French driving licence rather than a British one. You have to complete a Highway Code test (probably in French, in France) before you can start driving. You then need to take a minimum of 20 hours (normally 20-25 apparently) with a French driving instructor. Finally your over-28 driver, having held a full driving licence for at least 3 years, can register with the learner's designated driving school and then (and only then) start accompanying your learner driver. In the UK any full EU driving licence (of the correct class) is OK to supervise a British learner driver, so it may be the case in France as well.
Your UK driving insurance will most likely not cover a person driving on a French provisional(?) licence. And of course, getting a French driving licence probably requires you to live there anyway (although as an EU citizen, at least for the time being, you are entitled to obtain one in the country of your residency)...
It's almost certainly not a sensible option.
(as an aside, it's almost like anything that the EU hasn't standardised across countries is a massive PITA if you are from the 'wrong' country... but you know, EU bad, strong and stable good, those EU beaucrats will give the UK a great deal, the best deal, we have all the best deals, once May talks to them sternly enough... and strong and stably enough...)