[British pipes v French pipes]

I am new to France and wanting to take an English bathroom out there to fit in our chalet in 05 (Haute Alpes).  I understand that French pipes are 10,12,14,16mm etc and UK are typically 15 and 22mm - correct?  Is this going to pose a problem to our English plumber who is coming out with us to do the job?  What are the usual ways of solving the connections & what essential bits should he take out with him? 

[Returning from SE France with empty van]

We will be driving back from SE France (PACA, Hautes Alpes; near Briancon actually) on weekend October 9/10 with a nearly empty 3.5 tonnes, long wheelbase van that takes quite a lot of stuff. 

If anyone has things they would like transporting back to the UK get in touch.  We leave the UK next Monday August 30th.