Pottsy..........this is how I see it. When one drives a car in a Country other than the United Kingdom you are required to have the documentation that the other Country requires. But if you drive a UK registered car abroad i.e. your car in France, then other than the legal requirements such as valid insurance and a driving licence issued in the EU, you are covered.
To drive in France without an MOT is not an offence against French law no more than you don't need a tax disc to drive in Germany etc.
What is an issue is whether your own insurance company require you to have a current MOT on your car at any time within the insurance date range to remain covered.
If you are travelling abroad and return within one month have the MOT done before you go, as one can, and on your return you are covered.
If you are out of the Country for more than a month you can still have a UK test (anytime it does not have to expire) then you start a new 12 months then. OR
make an appointment for a test immediately you return. But if you do that you must drive to the test centre and not deviate your direct route. eg Dover to a garage that day.
Best advice. Get the car a 12 month MOT before you go.