Hi StanyeWest or should that be StanyeNorth - North London clay should let you grow acidic plants.
A camellia avoiding early morning sun would be nice - evergreen shiny foliage, reds available, spring flowering (if you are near an Aldi - reaonably priced ones are usually available in the new year)
A Nandina domestica - sprays of creamy flowers in May/June, evergreen with different coloured foliage throughout the year, red berries in winter.
A Hibiscus for summer flowers - red available
Full shade - Hydrangea petiolaris is a climber that likes shade - bright green foliage in spring, white flowers in May, yellow leaves in autumn and a tracery of red brown stems in winter - it would need some support in order to help it climb but it is a lovely plant; maybe ferns - Monty Don planted some on last week's Gardeners' World.
I'll have a think about your shady side - I'm assuming it faces north. No sun at all not even one end or part way up your fence? I'm assuming you have a fence...
Hope this helps.