I have maximum NCB on the car insurance here in UK. It needs to be renewed next month and I want to go with a company that will transfer this over to France. Is this possible? Any advice or suggestions
Short answer: Yes, it's possible but you have to work a little...
We bought a car in France last month. Strictly speaking I haven't had a car insurance policy in my name since leaving Australia in March 2015. That's almost 20 months without cover. Some insurers have an 18 months cutoff, after which they treat you as a new driver (ouch), some have a 24 month period (phew!).
Before leaving Australia I had full, protected no claims bonus and got my insurer to put that in writing along with a statement saying I hadn't claimed for the duration of the policy. I was insured in the UK for a year in 2012 and before that in Aus for a further 8 years. Every time I change country or insurer I had the same bit of 'no claim for duration' paper so I can prove over 10 years of insurance with no claims.
I found a local AXA broker in France who would accept this and give me full bonus malus. AXA in France also have a British speaking office (Google "axa in france") if you want to talk in English to someone. Credit Agricole would also accept my foreign record and were actually cheaper.
Side note: there is a wonderful chap in our local Credit Agricole who speaks perfect English and is a lifesaver!
A French friend of mine pointed out that even if they aren't the absolute cheapest insurer you should take a policy for at least a year with anyone who will respect your foreign NCD. Once you're in the French system with a decent bonus malus you can then go wherever you like on renewal.