I have seen dwarf buddleia in one of the plant catalogue email things I get sent so they do exist - white, pink or purple if I remember rightly. I think buddleia's do tend to spread a lot though but I am sure the ones I saw were called patio buddleia and could go in pots.
I like semi evergreen honeysuckle - we have one which has bright orangey flowers on it. honeysuckles also smell lovely.
lavender - big favourite of mine and bees love it.
californian lilac - erm is it called ceanothus? bees love their bluey purple flowers too.
hebes are nice bushes and can be different sorts so different colour flowers.
Camelia bushes are lovely if you have the right kind of soil - can't remember if it has to be acid or alkaline but if you see lots growing where you are then you should be fine, if not then you would need to check.
We have a magnolia grandiflora exmouth tree which I LOVE, and also a Forest Pansy tree, both are quite small but beautiful.
you could have a little patch somewhere to just sow wild flower seeds, I try to have some of these just purely because they look so natural and pretty and the bees and butterflies flock to them.