I am in the South, lovely but expensive but lots to do and lots of expats some doing what seems to be the same type of thing as you will.
I Can't really help with tax ( and you seem to be getting help with that).
Positives for me are: climate and way of life. Bright and sunny nearly all the time but still have seasons. At the moment the sun is out, the trees are changing colour and it's simply beautiful.
Lots of outdoors activities, lots of places for horseriding etc.
My french neighbours have been lovely and very welcoming, a real sense of community. (-unfortuately many have now left all at once but i am sure the new ones will be lovely as well)
Healthcare has been great. ( we have a private plan). If you want to see a specialist you normally just make an appointment direct ( recommendations from doc or friends) and so rarely a problem with waiting lists ( three months was the longest recently for a non urgent appoinment, which could have been much shorter if i did not want a specific person).
Schools a bit more tricky because of the ages of our children but if they were younger I would have had more choice. It will depend on your children and their strengths ( french schools seems to be quite academically focused, but i don't have much experience of this). Ours went to an international school which was good for them.
Overall Ilove it (but a bit homesick at the moment for a variety of reasons, but it is easy to get back to the uk and see family etc so its manageable).
My advice would be check out the schools throughly and try to make sure they are a good fit for your children.
Keep a house in the uk if possible ( we sold and now I worry that in the future we could be in trouble - as someone said above we have done a lot of work on our house with no return).
Check carefully where you are going to be based. Places look lovely in the summer and dismal, empty all shut up in the winter ( we nearly bought somewhere that looked stunning, french markets, lovely scenery etc, but in winter was v v quiet and little to do). We are now twenty minutes from a large town ( stunning town) so there is always something to do.
Buy somewhere on a bus route into the town. We did not and spent our life as a taxi service ( was okish but the children got fed of asking all the time and would have liked a bit more independence). Don't be fooled like we were by the bus stop for the school bus!
Make local friends who are not going to leave. ( many of my friends both expat and french left all at the same time!)
PM me if you want to know where I am and any questions.