I've found recently when I start the car (only when cold) the starter motor over runs a bit. Is there an easy fix for this or will it need changing?

 

Leave it alone. Mine does this and it causes no problems other than you get a little bit of a noise for half a second.

Of course, you can remove the starter motor and have a fiddle, but if it isn't doing any damage (and it won't be) then why bother.

 

Dirt in the inertia gear?
Looks a PITA to pull the starter, so i would live with it too.

 

I think its common, mine does this too. try searching death rattle, you'l get both TCT's (Unfortunatly) and this problem.