Welcome to the Club, Nigel.
I have always been a little curious about extended warranties. I retired in June 1999 after 29 years of company cars and after buying my company car [Toyota Avensis] and later used it in a part exchange for a Rover Sterling only 8 months old with the remainder of a 2 year warranty I noticed that the warranty would only remain valid if I had the Rover serviced my the main dealer from whom I bought it. The cost of a full service in 2001 was £325 +VAT. A week later I found a flyer on my car advertising a mobile mechanic trained by Rover and who had worked at the main dealer from whom I bought the car. The cost of a full service was £70. I am from Lancashire like you and I quote "In the spirit the made Lancashire what she is, I'd rather be drownded than done" I had my service done by the mobile mechanic and who for the last 19 years has serviced my cars. The AA does the breakdown service, but I have only used them twice because the cars have never failed me. I reckon I have saved about £8,000 over 19 years. My current car for the last 7 years is Jaguar 2 type. Any repairs that have needed correcting -- One sensor, 2 EGR valves and a water pump in the last 7 years have all been Jaguar parts much cheaper than would be charged by a main dealer, diagnostics charged by Jaguar are £164 -- my mechanic £20.!
So, that is my position. I cannot advise you how you should go, but finding a good mechanic who loves cars is a good move.
Regards,
Peter.