In the old days we could jump into any French club glider and
go flying, as Ariane is doing here. Alas, as is common knowledge, this is no
longer possible - well, at least, not with the same freedoms as before. It is
possible to fly French gliders at Sisteron provided the pilot is regarded as
"under instruction" - this usually means not straying too far from
the airfield. The local instructors have been known to be flexible with a
very few of the more experienced Brits about the word "local" -
occasionally Briancon, 100km away, is considered local enough - and have
allowed them to fly French club gliders.
The only other option at this time is to get a European
Glider Pilot's Licence - probably not that difficult in theory although the
language may defeat some. Jacques Noel was rumoured at one point to be
coming over to the UK to coach pilots to the required standard, but nothing
further has developed so far in this direction.