Posted: 07/03/2014 at 12:53
As already suggested, Euonymous are great for this type of location. I bought 3 (in 4/5" pots) for £10 last year in my local B&Q so good value. They've put on good growth already.
Japanese anemones will do well and give late summer/autumn colour and a bit of height. Pinks and whites readily available and they'll seed around - some people have problems with them being invasive but I've not found that here. Jacob's Ladder (Polemonium) in whites and blues, and Dicentra (Bleeding Heart) in pinks and white,both love shady positions. You can plant snowdrops and crocus etc for this time of year. Heucheras will do well and there are bright colours of green and gold as well as the more common purples, so they brighten up this kind of aspect. I have Lime Marmalade -self explanatory! A decent plant can be split and grows away quickly, and they also seed around. Fatsia japonica is a great evergreen for shade and has big, tropical leaves. Grows quite quickly. I have a Pernettya ( now called Gaultheria) which will grow in shade, is evergreen and they have large berries - pale pink or white.
Take a look at a specialist shade nursery called Long Acre plants online. I've not personally used them but they have loads of ideas.