I made my hedges/bocage in the same way as mwnciboo except I found that the jumbo craft sticks had a horrible habit of warping as soon as you put any paint or glue on them.
In the end I made the bases for my bocage from cheap vinyl flooring tiles that I picked up from poundland. You can then cut them to any shape you want with a pair of scissors. I then used cheap spray glue (again from poundland) to spray the underside (this is already sticky, but not quite sticky enough) and then covered them in sand. I then painted them with cheap brown acrylic paint (this time from Wilkinson’s) and once this was dry I stuck foliage clusters onto them.
It took me a couple of evenings in front the TV but I’ve now got more than enough for a 6x4 table. The whole lot cost me about £10 and £7 of that was the foliage!
The same vinyl flooring tiles can also be used to make roads using the same method. Just paint your roads brown, black or grey depending on your preference.
*EDIT*
Here is a picture of a game I played recently using the Vinyl tile based hedges and roads. Not the most professional looking, but considering that 2 packs at £1 each made more than enough to cover a relatively busy 6x4 table, it's well worth trying out.