Got home yesterday and when I moved the car later I noticed that there was an oil spot on the drive around the size of a pound, we went out for a few hours and came home there was no new spot there this morning. I'm not going to get concerned at the moment as it is only small and it could be nothing but is this common? And where would it be coming from? It appears to be coming out in the middle of the plastic cover so I can't be sure of the origin.

No, it's not common in my experience.

It could be something as simple as a bit of spillage from last time the oil was filled or topped up. Only way to confirm it is to get the plastic cover off and look for stains, drips etc. Clean everything up and keep an eye on it for any recurrance. As you know leaks can travel a surprisingly long way from the point of origin to where it actually drips off from.

Was it a dirty blackish oil spot or a clean yellowish oil spot? if the latter, and you have a cat, don't taste it!

Is your brake fluid level OK?

Dirty black, all levels are fine at the mo