Scenery Warhammer 40.000

For my Warhammer 40.000 armies, there are also a few scenery plans, but not at all as many as for the Fantasy part.
I would like to make some ruined buildings to make out a small settlement that has been bombed and burned, as some of my Imperial Guard units are specialists in urban warfare (according to their fluff).
This will also work very well with my Space Marines, as they fight under all contitions.
My idea is to make the bases quite similar for the marines and Guard units, so that they blend in when used together for games of Apocalypse.
This means they will have dark bases with some flock or lighter stones appearing somewhere. For the first Space Marine bases I used black aquarium gravel, but I am almost out of this now, and will try a little experiments to see if I can use coal crushed up for brewing wine/beer. I will also use the Warhammer scenery set for some of the bases.

Ideally I can make a building with four walls in the middle of the town, and have different ruined buildings going outwards from this. But the exact set-up will vary from time to time, and this isn't really something I will plan too much until I start to build.

I would also like to have some other terrain, like barricades to use in the city, and an Imperial Bastion, and/or a Fortress of Redemption, and some Skyshield Landing pads. I will also make some terrain outside of the city itself, like the Battlescape set, some craters and hopefully some self made bunkers or other small scenry pieces.