What a useful post! - thanks again for the tip Susie
- After reading all the replies, the only plants that came to mind that were not mentioned were:
Lithodora diffusa, "Heavenly Blue" beautiful blue flowers and a favourite of the solitary bee
Anthophora plumipes. Also, it is an effective ground cover on sunny sites.
Broom Cytisus x racemosus, loved by all sorts of bees, bumblebees, moths, shield bugs, snails..and its got a very long flowering season May-October.
Good luck!