I finally managed to beg some nylon net curtain offcuts from a lady at work for the cammo nets. I've attached these to the trees and bushes on the stand with super glue, then brushed PVA glue onto the net and scattered meadow green flock, then finished off with a sort of dry brush of Tan Earth and PVA glue. The overall effect comes close to some images I found on the web of cammo nets on artillery emplacements.
As always, great to hear any opinions, especially if I've got it wrong.
Thanks for looking.