Dwarf Hebes - they're evergreen and flower in the summer. Make sure you check the name on the Hebe Society website for hardiness, though. The information on the plant labels can be misleading.

Heucheras would also look good, but you need to check each one to see if it prefers full sun or part shade. They're all different.

That's great. Thanks for your help. I'll check it out!

You're welcome. Just type 'Hebe Society' into google, and you'll find it. :-)

And I have my hebes underplanted with low growing perennial hardy geraniums such as macrorrhizum Biokovo and Cambridge ( I think thats their names ) which are evergreen so that bed requires zero maintenance because the geraniums keep the weeds down too.

All of the following are low growing,evergreen and flower for 3 weeks or more

Dwarf campanula , dianthus, thymes,ajuga ,some sedums .

Lavender would be there all year round, but especially attractive when flowering in summer. It just needs a trim after flowering.

Yes I agree again . Lavender would also be a good choice but just make sure you go for one with a nice compact habit. Some can become very big and very untidy. Munstead is one of my favourites

Thank you so much everyone. I am a novice gardener and a busy working mum with a fairly big garden....learning as I go along.