Thanks everyone. I've got the French VFR pack and Sydemon so feeling fairly confident. I just wanted to be sure that if a) Skydemon went down / Ipad broke and b) I didn't get handovers between units that I'd be confident enough to know which frequency to dial up next.
From what everyone has said it looks like I should call Lille on first contact and then all being well I'll get handed over all the way down France.
What would be really handy would be a French equivalent of the UK LARS map that makes it very clear where the boundaries between Flight Info sectors are.
Thanks!