You don't state where you tried to use your cards. The problem you had is more likely to be due to the age of your card or the pump equipment.
Not all UK issued chip and PIN credit or debit cards are recognised by the automatic pumps installed at French petrol stations. I have recently issued chip and pin cards (Nationwide and HSBC) which work in the local Leclerc and Auchan supermarkets in Lot et Garonne (Dept 47). It's is a bit of a lottery, however more and more French supermarkets are installing readers that work with British issued cards. If you are really stuck, offer to pay a local in cash if he uses his French credit card to pay for your fuel. It helps if you have some rudimentary French! You may get a funny look at first but if you show him/her the colour of your money then you should be Ok. It's worked for me a few times. But, to explain the normal practice - you normally put the card in the machine - make sure it's inserted the correct way. Put in your PIN and "Validate" (green button) then choose what fuel you want (SP 95, Gazole etc). Once the machine recognises your card it will ask if you want a receipt then ask you to remove it before it dispenses the fuel.
Good luck next time!