My garden has the same aspect. For winter/early spring interest, how about some bergenias? Go for a variety where the leaves turn plum-purple in cold weather. Lots of plants will be happy in part-shade. Tricyrtis formosana (toad lilies - purple spotted) and Aconitum (monkshood - deep blue) provide flowers from late summer to early autumn. Both can be ordered from J Parker (I'm guessing you're thinking of ordering from there, as they misspelled the dicentra peregrina). As you say the site is a bit windy, how about some grasses? And don't forget ferns - the evergreen ones provide useful colour in the winter months. Athyrium nipponicum pictum is deciduous, but it does have beautiful silvery fronds. Dryopteris erythrosora (the autumn fern) is evergreen and has lovely coppery new fronds. Also, add to your stock of spring bulbs. Crocuses have the annoying habit of only opening up their flowers in full sun, but they and most other bulbs are happy in part shade. And fuchsias, of course, like shade and are fairly wind-resistant (often planted as hedging in coastal districts).

Aquilegias will flower from May to July. The great thing with them is that they hybridise freely, so each year your stock will increase, with hopefully some interesting new colours.

A useful, if slightly quirky book about gardening in less than sunny conditions is "Gardening in the Shade" by Margery Fish. As it was written well before global warming started playing havoc with our gardening calendar and our ideas about plant hardiness, her selections should be suitable for a more exposed site.

Hope this helps.
Ornata