I've lived out the UK for 12 years - not in aviation just a customer - and I have seen many people fail at living abroad for the reasons the last poster gives.
It doesn't matter what job the main breadwinner does (got to be PC, don't assume it's the husband, although it usually is), the partner gets all the problems. He's off at work, no worries, while she's maybe given up a job to go there, maybe got kids trying to settle into a new school where they don't understand the language. In Asia particularly, the expat wives' societies can make or break it, if the mrs cannot get into the circle, she's stuffed. In Jakarta, we had the British Wives Association, the BWA, aka Bitches, Witches and Alcoholics and many many times they just didn't like the new girl on the block and she had no friends. So much pressure on the husband to go home. This may not apply in France, but in my experience - I have some friends who have retired to La Touraine - there are quite a few Brits wherever you go and she will have to be able to mix in with them while you're off in the wide blue yonder.
Tax has to be your last reason for going. Quality of life should be your only consideration, and you have to be prepared to put in a lot of work initially.