Most of the painting has now been finished. I re-varnished the canal water surface with another layer of Klear (Future in the US) before painting the exposed edges of the layout. I had seen a dark grey paint in B&Q which I was going to use, but on returning home I found a tin of Ronseal water-based black paint in the shed and after adding some parchment coloured acrylic paint to it, I had a slightly off-black or dark grey paint (I though pure black might have been too stark).
I used a large artists brush to paint the edges. It took three coats before I was happy with the finish. I then sanded out any brush strokes before adding a fourth layer of the dark grey paint and finally varnishing it with Dulux satin varnish.
I have started to add vegetation to the layout, using any wargaming flocking or tufts that I had in the shed. I stripped a couple of HO-OO scale trees of the foliage before adding it over the artificial garden hanger material with spots of superglue. You can see the effect on the trees or bushes along the back of the layout and against the scenic back board.
Even with all the layers of Klear, I still think the water effect could be better and I have ordered a bottle of Aqua Magic via the Internet to see if I can get a glossier effect.