I went up to 2500 grit on my mirrortop to get out all the scratches.
You can buy packs in Halfords that go up to 1500 or somewhere in that vicinity, and the higher grades (should you want to go that far) can be bought from Axminster.
Problem with wire wool is that it dintegrates as you use it, and the bits get everywhere. "Mirlon" is a better product that replaces wire wool, and comes in a similar range of grades. Seems to be mainly a US-based product at the mo though.
However, for guitar bodies, sandpaper is good enough. My experience is that c1000 grit is fine as the final grade for sanding. Again, IMHO, the final grit grade is not the most important aspect. It's more important to gradually move to a finer grade only once you've removed all the scratches that you can with the lower grade papers. Then, 'tis important to apply the finishing oil in multiple very light coats rather than just slapping the stuff on. Rub-down between coats if it dries unevenly.
It's more important to gradually move to a finer grade only once you've removed all the scratches that you can with the lower grade papers. .
What he said. It's most disheartening having to back a couple of grades (as I had to on both the Walnutcaster and Explorer) . If you've left any sanding marks in from rougher grades they just get more prominent as you continue to finer grades