Hi Zok and thanks for the feedback.
The product I use for shaping groundwork is called Mix-It. It is an instant paper mache so it is basically dried up and ground up paper that mixes into a textured and spreadable goo when water is added. To this I also add a handful of sand (I saw this little trick on another post by a lady who did a great dio of an old truck, can't remember her name).You would be able to buy it at a craft or art supply store. I'm not 100% sure but I thought Celluclay was the same thing.
I shaped the ground with white packing foam (like you find in electrical appliance boxes) and then spread the Mix-It over the top. It needs a few days to dry so put it in the sun or in front of a fan.
After it dried I added the grasses from Dioramaterials. They are called Green Grass and Real Grass and when mixed together look very realistic. In the gully there are also Reeds from Green Scene and bushes from Dioramaterials also. There is also some long grass from Woodland Scenics. Rock mix from Noch makes the rocky outcrops and some railway ballast at the bottom to simulate crumbled rocks.
The thicker bushes on the ground is rubberised horsehair. Great stuff which is available from the 4D model shop in the UK.
Both of the above companies got their products to me in Australia within a week.
So that's it. Again, thanks for the feedback.
Glen