Your tank is the same depth as mine, I have put a 40mm strip of black foam board (black foam sandwiched between black card) around the base of the front and sides of my tank so that you can't see all the substrate, just 20mm of gravel. This stops you seeing the gritty stuff at the bottom (maybe I'm too fussy about this sort of thing, but hey, it's gotta look good).
When I redo this tank (or should that be undo?) I will look at putting Daltons Aquatic Mix on the bottom, rather than the sand. It was all I could find at the time I set it up, but now I have found a source for the proper stuff.
I put the substrate in first, half filled it with water, then planted. You don't have to get wet all the way up to your armpits this way, even if it is a small tank.
Then filled to the top, waited for the muck to settle, added filter, then three Corydoras.