This is difficult - hedges and particularly conifers 'suck' the nutrients out of the soil, so not much will thrive in this position.

Try Symphytum 'Goldsmith' or S.'Hidcote Blue', Vinca difformis, Hedera (you can get pretty variegated forms), and Geranium macrorrhizum. They are all spreaders, so you'll have to keep them under control.

Bergenia and London Pride seems to relish getting further back under the shrubs in my border.

It's the conifers that are the difficulty, Rozalia, or I'd agree completely.