Successfully used a UK card in a fuel station (not supermarket) in Le Mans. But been caught out by this kind of thing before, so it's a good warning.
I arrived in France at 00:30 on "Bastille night" one year, and headed for my St Omer hotel, expecting to find fireworks and street parties. Nothing. Bit disappointed, but maybe I'd missed it all...
my last bike trip in april showed all the machines now accept our cards.... chip and pin stuff. they will still make you sign it after pinning though