Thanks for the response guys, do you know what the part number is for the camshaft position sensor is? I did try to look at the RCM but I was really struggling to get it out of the protective case and I was worries about accidentally damaging the circuit board. I think I may just replace the RCM myself as I'd rather not make a complete mess of the current one but trying to solder it.

What I mean by not turning over is that the engine will not start at all, you can hear the starter motor but the engine doesn't start. It can take a few try's and it's pretty intermittent, ive noticed that this tends to happen in between stops after I've been driving.

In relation to the air pump I can hear it working when the car starts, the check engine light keeps turning on and then off again on its own accord. Ive got 62000 miles on a 2004 model.

And yes Sonning is a lovely area I'm not too far away in Shinfield and love it