Righty then... - time to start work on the car again....
I've replaced the engine earth strap (well, added another one from the same place where the original one goes to, directly to the bat) and the starter motor is still playing silly buggers.... - so i've now got a new one on order - that way at least I can rule that out of the equation.
'm just going to go and take the cooler etc off again, and re-check everything that i've done to the car thus far to ensure i've not missed anything silly....

Just one thing - I presume that Snap-on falut code diagnostic equpiment will interface with the car? - or will the coilpack conversion, and chip just cause it to not give correct readings?

I'll let you know how I get on!