Could I plant a few medium shrubs like skimmia along the wall maybe one on each wall. Any suggestions on medium size shrubs as garden is quite small.
Skimmia is a good shrub for light shade, tends to broaden with age, but could be pruned tighter. Camellia is an excellent wall shrub in a shady place and can be trained easily.
Aucuba is good in shade and trains well, also laurustinus. Fatsia makes a fine stuctural shrub in light shade.