Thanks for the responses. I did think the Halfords battery was a bit expensive, and, as yet, have not installed it. I was concerned about my warranty. I would hate for Fiat to say that they would not do something under warranty because of the Halfords battery. I have my third year warranty + 2 more years that I purchased from Fiat when I bought the car.
As for all the wonderful faults, yes I do get many. Usually that my coolant temp is high, even on a frosty morning when I first start the car.
Also, after sending my initial question, I thought I would have a closer look at the battery. I know it is supposed to be "maintenance free", but under the strap that holds it down is a access panel to add de-ionised water. I popped it off, and sure enough all the cells were pretty dry. I topped them up to the correct levels, and went for a 10 mile drive down the motorway, since I don't have a charger. I don't know if that will fix the problem. The sight glass on the battery (do they mean anything?) has gone from yellow to black, but not green. The car did start this morning without a problem. The battery may be knackered due to low water, but who knows? Any thoughts?
Thanks