Well, I seem to have stoked a hornet’s nest - and apologies for that. It does show though how much misinformation and confusion is out there - the biggest challenge I’ve had is trying to get straight forward answers to questions about the tax we’ll pay when we move to France, (especially given the complexity of earning from a UK based limited company that I own half of). It does seem to be a minefield but I think I have a basic understanding now. Actually, as we’re taxed on household income in France, rather than individual, I don’t think we’ll have more tax to pay. The other question is what happens if, one day, I sell my share of the UK company whilst living in France, but that opens a whole new can of worms! 
A lot of the advice and information has been really, really useful - and thank you all for taking the time to respond to this thread.