Be very careful with France....
The fifth republic has become almost Stalinist since M. Hollande arrived and taxes are very much on his radar. If you are deemed a resident, your global income is up for grabs. Bear in mind that even under the dual taxation treaty, any net UK income that HMRC have finished with will be taxed by the French.
It is very easy to be seen as a resident; you may be out of France 365 days a year, but if your family are there.......