Thanks for the information and the replies...

I've had the sensor replaced and the 'cutting out' has stopped.
The fuel leak is a bit odd. It's completely stopped. I've run the car a few times and drove it to Penzance and back yesterday (30+ miles) and not a drop, no smell nothing.
I think it's still a good idea to change the filter and I'll do it when I get back as I'm going away on Thursday.
One thing that I didn't mention before is the coolant level. I've needed to top up often but I've had no obvious signs of leaks, no water underneath car, no wet areas under the bonnet.
Got the garage to do a pressure test today and they reckon a have a very small leak from the electric water pump. He said it took a while to find and that it's seeping out. They reckon a new pump will set me back £104 + VAT. Does this sound about right?
I'm quite happy to fit it myself doesn't seem to difficult a task.
Cheers