At this point I was much happier with the appearance of the bases, and next was to add the foliage and grass. The finished product....
The above image hopefully gives an idea what the bases look like together. The next image gives an idea of scale.
The figure behind the hedge is an Artizan designs 28mm WW2 US Airborne rifleman. Obviously you cannot tell from the picture but the figures base is butted up against the hedge base. For the record the model is based on a 2p coin.
With the foliage and scatter added, I sprayed the bases with Woodland Scenics scenic glue, using the handy spray top from the aptly named Scenic Sprayer. (The foliage and scatter was glued on first with either PVA or Woodland Scenics hobby tac glue). Once the second layer of glue was dry I sealed the hedges with Games Workshops Purity Seal spray varnish.
Overall I'm pleased with the result but would change a couple of things. Firstly, the cork ridge I should have made slightly wider, perhaps only about another 5mm. This would have meant I could have put wider clumps of foliage on top, filling out the hedges a bit more. Also made the bevel on the edges of the cork steeper in places, to make the slope more pronounced. I might also try not to 'spot' the static grass onto the base next time. In the photos it looks odd on top the turf (well to me anyway).
Next to make more straights, corners, T-junctions and gateways/openings. The MDF bases work fine and I'm hoping the same size base will serve for making bocage.