Hi Mateyboy, I missed your build diary thread.

As long as you get at least 3 good colour coats on the neck you shouldn't sand through to the primer. The thicknesses of the coats shouldn't be that noticeable compared to the fretboard. Just wet sand it with at least 1200 grit paper and cut and polish and it should look sweet. Obviously allow plenty of curing time.

Fretboard finish there are plenty of oils and waxes available. Dingo wax works well available from the PBG shop