Well, I got my flocking supplies in the mail today!
I bought 4 x grass (one for each board), 4 x medium grit, 4 x small grit, and 2 x scatter vegetation mix.
What I discovered was that it will take me around 1.5 to 2 tubs of grass for each board - so I don't have enough fake grass at all :(
So I'm going to complete the table, one board at a time, probably with a few weeks between each board depending on how my supply gathering goes.
Anyway, I've got grass onto one board now. Once I saw it would take more grass than I had thought, I decided to have some larger areas where muddy dirt/gravel will go later on. I also decided patches of grass will be sparser - with more dirt - on top of the slopes on each board. Here it is with the glue still drying.
The trick to getting the most use of your grass, is to get a lump between thumb and two fingertips, and rub your fingertips to sprinkle grass over patches of glue, until it looks thick. Then - before the glue dries - stand the board on its side, and bang on the bottom of the board, so all the excess grass falls off onto some sheets of paper. You can then bend up the sides of the paper, so the loose grass gathers in the middle, and tip it back into the tub for use on another patch of grass.
Here's an example. After adding grass onto the board, my tub looked like this:
Starting to bang on back, so grass begins to fall on piece of paper
After gathering back all the loose grass from the board, the tub was almost full again!