Thus clarrified (not the leman gas field), the cross channel service from Deuville is very good. Once past the coastal area, there tends to be an element of being on your own (Paris Info v disinterested)
Watch out for the danager areas when heading South. There are a number of VOR/DME to follow to keep clear of the central area and get a good track SW or S.
Plan well, have a number of diverts available, and pick fields with radar for this.
I did Barcelona via this type of route (refuel at Rodez). Quite a hike. Watch out for the weather in the SW as well. High ground to the left (East).
h-r