aubretia, perennial alyssum, creeping phlox, thyme, ivy all spring to mind.

Thank you, I will check them out

I quite like trailing petunia and trailing lobelia.

And creeping jenny

Cerastium tomentosum and Saponaria ocymoides, though you must watch they don't spread too far and reduce their size if necessary. Iberis sempervirens is another one, along with Helianthemums, both of these are evergreen, need clipping over after flowering.