I found an article on Armorama (http://www.armorama.com/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=116) on making sand bags with Milliput.
Not much to say on this process, mix Milliput, shape to something resembling a sandbag, place on diorama base - repeat until finished.
Once all sand bags have been made and placed, I mixed up Papier Mache mixture with PVA glue and Tamiya Diorama Texture Paint Soil Effect and Woodland Scenics Static Grass.
I figured the Germans would have built up dirt from the banker in front of the sand bags - this mixture kinda gives the impression of soil being turn over.
Added the mixture with a paint brush, then changed my mind again and dusted the area with Earth Blend from Woodland Scenics and then randomly spray Woodlands glue and added more Static Grass - blowing this off to get the grass to stand up a bit before shaking off the excess.
Repainted the diorama sides again with Gloss Black - not as good as before, but it'll do and painted the Wood with Tamiya XF-59 Desert Yellow. I'll go over this later with a stiff brush and oil paints to create the grain effects of wood before weathering it further.
The slope I've created in front of the Sandbags is effective. Due to re-working the base, I've create more features in the existing ground work, instead of a level area, it looks more what you would see in real life.