Ok sweet I will get the Hycote Grey primer then.
As I said I really get on with the Hycote matt black, I use it to undercoat models I think its great.
Basically I plan on making some scenery using the same technique as Winters SEO does on this video:
https://www.youtube.com/watch?v=VYytzUYLsV8&t=301s&list=PLmSE5b9DbDz3ihjLPVgu02-pyLLbQbXHA&index=2
Basically spray flat
MDF (but this would work on any flat surface) with a textured spray paint, then base coat black, then more lightly spray grey over that, so it'll still look dark.
He then does some drybrushing over, personally think the end result looks amazing for how little effort it takes.