Hi Paul,
There is no "continental" style of gas connector - many are the same - but the connector is specific to a type of bottle.
In the UK, the valve-head on a butane bottle is different to propane, also sub-10kg bottles will usually have a threaded connector and over-10 kg bottles may have a clip-on connector.
In France you have three main suppliers of LPG - Total, Elf and Shell. Find out what suppliers are in your local area and just buy the connector for that make and size of bottle.
But what is the connector?
If you have a low pressure system - with a regulator on top of the gas bottle - then you will need to replace the two regulators for the correct type (gas and bottle fitting) and you should also replace the flexible hose if it is the thin wall type.
If your automatic changeover system uses thick wall tubing (about as thick as your thumb) with threaded connectors (not jubilee clips) then this usually has a life expectancy of 3 to 5 years - use sensible judgement depending on the date stamped on the tube.
If you have a high pressure EN system - with a single regulator mounted on the gas locker bulkhead and high pressure pigtails that go directly to the bottle on-off valve-head - then you need to replace the pigtails. I think this is unlikely as I don't know of a high pressure automatic changeover system - manual yes.
Do you need a CORGI gas fitter - no - they are usually only certified for household work - someone at your caravan dealership should be trained to handle LPG systems.
Would I do it myself - in my case yes - but then as a Chemical Engineer that designs process control instrumentation for petrochemical refineries, I should be able to, and although I work at a computer I'm rated to work on systems operating above 2000 psig - I'd still check my work methodically and repeat the necessary leak tests after a settling in period.
Robert