Ramshackles,
I moved to the Limousin area 3 years ago and will never return to the UK, even if it was financially possible, which it ain't.
As you will be working, you will be in constant contact with French speakers and you will learn fast, I have to have one-to -one French lessons each week because I'm retired.
The most important thing to remember is that English is just anglicized French; the accent disguises that fact. Only the who, which, where, when, why, what and how remain from our original pre-Norman language, along with the earlier words that the common people used, like bury for inter, in fact all the words associated with quality, law, government and authority are French based. There are more words in English than in French because of this.
Gender was dumped when the Saxons, Danes, Vikings, Jutes and Angles had to communicate with each other in the 800's. I wish I had known all this stuff back when I did French at school! It would all have made much more sense back then.
What do I miss from Britain?
(you can get Marmite in Carre Four if you look).
White lines on the roads.
Crystal Clear Bills for utilities. The French seem to think we need to have the relevant statute to read before we will pay a bill. Their obsession with numbers needs serious therapy. The code on my Orange Live Box (router) has 16 digits to enter. I think they must think it will serve them for when we colonise other galaxies. Google translate is a life saver but check it backwards first, it is a work in progress.
Advice: They do not have a telephone preference service so get a call identification phone and don't answer any numbers that you don't recognise otherwise you will be plagued with selling calls. Shops and offices often close from 12 to 2pm but are open later in the evening, some close on Monday too. Supermarkets have recently started opening during during the lunch hours though.
Allow 2 hours to open a bank account and they charge around 4 euros a month and for a bank card, that is Credit Agricole, but AXA may be different. Beware of some mutual banks where you may be liable if they go bust, like Lloyd's Friends, check the small print.
The internet is not used as much in France as in the UK, search facilities on French websites almost never work. I think that because the internet is mostly conducted in English, it never caught on to the same extent over here. Amazon FR is a pale shadow of Amazon UK but it is worth checking for some items because the delivery charges are often less.
Lyon was a nightmare due to roadworks, but hopefully it may be fixed now.
Apart from the forgoing, you will love France, it is like going back 50 years in some places to a gentler pace of life.
Final advice: When you go into a doctors waiting room or any shop, say Bonjour, even if you don't know anyone, it is impolite not to do so. Do not just launch into a question before that basic politeness has taken place. Bonjour and a smile will open doors for you.
Bonne chance!
DaveP