Posted: 05/06/2013 at 10:26
Whatever you plant here is going to have to compete with some pretty greedy plants taking water and nutrients out of the soil. It might be better to put something you like in a pot or trough than expect it to compete with leylandii and hawthorn?
It may be possible for rosa rugosa to do here, or pyracantha (prickly which may be a no no for you), maybe some ground cover like periwinkle - the newer ones are better in flower and not so invasive as thier earlier cousins. Early spring small bulbs may do well, flowering before the canopy thickens. Spindle shrubs are nice, good autumn colour - possibly wigelia?