Thank you for all the replies. When I had my service and Mot 6 months ago it was noted that the rear pads were under 4mm. last week I had an invite for a free complimentary check on things like tyres, brake pads,fluids etc (because of the brake pad notes from 6 months ago). I took the Car in today and they did the free check and the report said every thing was OK inc the brake pads and that no action was required !
I asked about the cost on here as I was fully expecting to need new rear pads. I will certainly get a quote from an independent if I require them in the future - thanks for all your help.