Update

After a few weeks of it being problem free the problem has come back again. Car is booked into Woodford Garage for the morning so fingers crossed.

It definitely seems like an electrical fault though.

Im not sure if this is related but when the car does conk out and I try to start it again, when I turn the car over the starter motor will spin very quickly and the rev counter will not move. When I turn the ignition on and off again and try again the starter motor will not spin as quick and my rev counter needle will move, the car will only ever start when this happens.

Ive actually recorded it on my phone so i might even put a video up as im sure it would be clearer to actually see what im trying to describe.

My wise old dad thinks it is an electrical fault and described it too me as something is not triggering it to spark but we are unsure what?