I live (for 6 years now) here in france and for years there was a real problem. Now as teh machines are updated they are (mostly) connecting every where, but they do need chip and pin. I can use my new visa card in my local Le Clerc, a little village super u on the road out of belgium near Verdun and in Dieppe. Those are the only places I have tried. All out of hours.
my local credit agricole works fine with Nationwide card, as do all teh cash machins in my local city. ( five out of five). None work with sainsburys. I think it very possible to find old machines that do not work, but since my new chip and pin i have had sucess three out of three attempts. But do carry cash ( esp some small notes 5, 10 ) That way at a push you can pay some passing french motorist for your petrol via his card. it was sunday, I was on my way back from German diesel bike rally, and i saw a gathering of motorcyclists in this little village super u.. so i thought if i go through the motions of using my card, and it doesent work, i can ask them to help, but it worked. My card is a tsb visa card with chip and pin.
for some reason my local post office stopped working with the nationwide cards i had back in the summer, i think because they changed over to chip and pin and at that time my nationwide cards were only stripe. I haven't tried the new cards in teh post office as I have been using the credit agricol machine in teh shopping mall where we shop.