Welcome Dave.

If you haven't already done so I highly recommend reading as many build diaries from the beginning pages to see what other forum members have done and encountered along the way.

That said, sandpaper grits used are typically 80, 120, 180, 240, 320 and once top coats have been done finer grade wet & dry grits from 1200, 1500 & 2000 would be the way to go.

Cheers, Waz