1 piece suits are bought by folk in the early learning stages of travelling abroad,yes me included till the penny dropped.

As the others have said buy a two piece,and the main reason the water lies in the fold of the jacket,the trousers are your second layer.

When you buy the trousers go for the concertina look!!! so when your on the bike they come down to your ankles.

Now!! the important bit,don't go buying a jacket like Alpinstars they have elasticated cuffs,so at any kind of speed they ride up your arm and the water runs down into your glove,the cuffs have to be velcro.

I'd like to be able to say I worked all this out 30 odd years ago but it's been a wet and at times expensive learning curve!!!,lots of money doesn't mean good.
Oh and if funds will streach Alpinestars 365's not cheap but they are the only thin gloves that I have come across that have Goretex as well,they do work,but you'll still need a pair of thin trials gloves if your going down south,your hands will cook in anything that is acceptable in the UK.

Cost?? the unlined jacket all of 20 quid and the trousers �15.

If I was in France the first place I'd look is Daffy Moto