Spring flower bulbs comes to mind as, by summer the area will be in shade.

Are you sure the nettles have all gone, they are bobbies for coming back again. Christmas box, Euonymus fortunii, Arum italicum maculatum (which shouldn't be invasive on poor ground with tree roots) Alchemilla mollis (which does seed around) Lamium maculatum, pale and light pinks and white). A selection of shade tolerant perennial geraniums (for examples see Long Acre plants website) If you find the ground is too dry for the latter add gel crystals to the planting hole - makes all the difference. If you have a large area blue comfrey spreads readily and bees love it - its also good for composting. You only need one!! If you think there's enough light and there's room how about forsythia. Also if there's room, Mahonia aquifolium.