Obviously you could just depart [France] from some unmanned farm strip
There is the small detail of your flight plan, which is compulsory as you'll be crossing an international border, being rejected due to your departure airfield being non-customs. Depends of course on how attentive/helpful the person taking your FPL is, but in my experience they are quite knowledgeable and will warn you if about to do something stupid.
The other thing is that if going to NON international airfields (basically, this means NON Customs airfields) you have to speak the local language
The exact language requirements are as follows (extract from the
French VFR Guide 2008):
LANGUAGES TO BE USED
Air traffic services messages can be transmitted in French or
in English unless “Fr only” appears on the aerodrome charts;
when it does only the French must be used. However French
pilots must use the French language except for training requirements.
Note: the abbreviation “Fr only” is systematically indicated
when the aerodrome is open to IFR traffic when there is no
traffic services organism
Note: aerodrome charts might be obtained, of course, from the
AIP
I notice, btw, that the "Fr seulement" bit seems to have disappeared from many of the VACs which used to have it (in fact, can't find a single one just now)--whether it's a misprint or something else I don't know.
transponders .. I understand they are not mandated in France
As I remember it, you can fly non-transponder in uncontrolled airspace, but it is compulsory in CAS. There should be a definitive answer somewhere on the AIP or the VFR guide referenced above.
Arriving in the EU from Croatia, you may as well be coming from Iraq.
Meaning..? The one time I've been to Croatia, I felt like arriving
to Iraq (with apologies to the Iraqis) when I landed in Graz. Bunch of square-headed bastards
But digressions apart, I recommend you
order the very useful VFR guide, which is only about £25.- including one mill charts and a couple other bits.
I also second the
Fly in France recommendation for practical info not found in the official docs, or just speak to the natives once there. The GA community in France is big and enthusiastic and they will usually be happy to offer advice (even to an Englishman
)