They unfortunately go only up to ~ 5000ft
Do not have them with me, although as I'm in France I'll try to have a look at them in the club tomorrow, but don't they go to 5000ft AMSL or 3000ft AGL, whichever is higher? For one thing, if they only go up to 5000ft AMSL, then my airfield is off the chart
You should just avoid "conversation" because many foreign ATCOs know only the stock phrases in English.
IME the French speak excellent English in terms of vocabulary and grammar (or maybe it's just that I've flown in Spain a bit too much), it's their accent that it's sometimes utterly unintelligible (and often it doesn't get any better when they speak French).
Strictly speaking, French is necessary where the AIP says it is, it might be "international" (as in, customs available) airfields, and even normally controlled airfields (outside of ATC hours). Conversely, it's also
not necessary at many smaller AFIS-only strips.
As has been said before, whether you can land on a particular aerodrome or not, coming direct from the UK, depends on whether it says "customs available" on the AIP. A lot of municipal aerodromes (grass strip kind of affair) are points of entry, the only requirement being you phone/fax in advance so they can decide whether they want to send a customs officer to meet you. I've never flown direct to France from outside Schengen so don't know the intimate details though.
But France isn't like the UK, where every piece of tarmac over 1000m is trying to be "London International [insert the nearest village name]" and is charging a fortune to land. You can land at say Biarritz for peanuts - the airports are subsidised by the local chamber of commerce, etc.
Fully agreed. It's such a pleasure (and affordable) to fly here
with PPR you can achieve a great deal, if you have the contacts.
PPR in France involves calling the number given in the aerodrome chart on the AIP (usually the local aeroclub) and asking about landing there. The reason a lot of places are PPR is because of local procedures/restrictions (such as no take-off and landings during lunch hours, dodgy approach procedures, etc.), and making those PPR is a way to force outsiders to get in touch with someone who can fill you in on any relevant details you need to know.
Of course, many of those are rural strips and they're not always keen on outsiders, especially but by no means only, foreigners. If you're not fluent in French, it pays to get someone who is and phone them up for you, then just say you were looking at landing there on such an such a date, and whether it would be possible and is there anything you should know, etc. As usual, a bit of courtesy goes a long way
Anyway, to the OP, have an enjoyable trip.