HI Kev
It can be tricky finding the right colour, but
Pine is usually good
any type of wood filler will do (i sometimes use plas-wood) it is only ever a temporary solution
and i don't like filling cork unless i have too.
cover the areas/fill the holes as required and wipe smooth, leave to fully harden (a day or so) and then
lightly sand with 800, then 1200 grit sandpaper, once back down to the cork surface, finish by rubbing with a piece of plain white paper
The trick is not to attack the surface of the cork witht he sandpaper, only to remove the excess film of filler.
Hope it works out fine
Sandy