He currently works in the UK but he still has a little Auto-Entrepreneur income stream in France as a sideline. He's effectively resident in both countries. We only have a home in France (he rents in London alongside his current contract work) but he could easily be in Dublin, Germany or any other EU country. The only reason I'm here this time is because we decided to have our 3rd baby close in age to No 2 and my pregnancy with No 2 was tricky when he was away.
I think you'll find it easy back in the UK - there is less paperwork and you can do so much more online now than when I left - things seem a lot more efficient (possibly smoke & mirrors). Food appears cheaper (albeit possibly lesser quality/more bulk produced?) but the pace of life is definitely different for us. That could be because we are in Canary Wharf where everyone is rushing about whereas in France we live in a little village but it does seem everyone is online, wired and zooming around. I've managed to resist getting a smartphone so far but crikey even my Dad has one - it's like when I'm in France I can sort of ignore all the technical wizardry going on - why do I need GPS on my phone to go to the Boulangerie? But here in London it would be really useful sometimes and I am very tempted to get a Tablet PC (apparently will be the Christmas present of choice this year in the UK and my mum is thinking of buying herself one for Christmas) so I am now feeling like the left behind kid.
Re: insurance - we kept ours in the UK with Stuart Collins who issue a 365 day green card as long as the car goes to the UK once a year - which we always did. Main reason being we changed our car (it's LHD but we bought it cheap in the UK) and didn't have the right paperwork to transfer it over. The garage in France wanted some ridiculous amount to issue a certificate of conformity - you have just reminded me though to ask in the UK before we go back to France as we probably will change it to French plates next year. But your point about insurance is a good one for us - to think about in terms of making sure we get our full no claims from the UK documented before we change over and then follow the paper trail in France just in case my hubby ever wants a UK car again. He'll always be working on contracts abroad, it's the nature of his work - there isn't much demand for IT consultants in the Herault :)