The automatic payment pumps I found only accepted Carte Bleu - my Visa Chip 'n' Pin wouldn't work.
The time before last we were on our way down, it was about 1:00am, we were off of the Autoroute and there was not one petrol station open.
In the end we realised that we had to get back on the Autoroute and, lo and behold, we found a aire with fuel that was open - appropriately named "Gasville"
An odd thing happened on the way back - my wife used her Smile card to pay for some fuel at the till - and it went through using Chip 'n' Pin! I was very surprised, it was the only time I have ever seen a UK card work in France using Chip 'n' Pin.
Hopefully this is just the start, and things should start getting a lot easier for us Brits over the channel!
As said above, I stick to a rule when driving in france - get to half-full, fill up at the next station. If at night, stick to the Autoroute, so you know that you can get fuel if you need it.