Thanks for all the support! Thanks Alun, if your profile picture is anything to go by, I guess that's not a good thing!!
Spent a few hours sculpting sandbags with the rugby on in the background. Also done some ground work and some pointing around the floorboards. Starting to look better.
I am after ideas now...This is going to be a radio/command trench, as per the pics below. Now do I fix the roof (only loosely dry-fitted in the pic), add the earth on top and then prime the whole lot, probably struggling to paint the inside, or do I roughly paint the inside while it's open, then mask, add the roof and blend the earth into the surroundings and paint/landscape the rest? I'm not convinced having it removable will work.