I expect that there are sunny and shady parts in the courtyard. These will need different types of plants. For the shady side try Saxifraga x urbium (London Pride) for a red/pink/white frothy effect. Tiarella grandiflora also thrives in shade and is VERY frothy but only 8 inches tall. Astilbes will enjoy partial shade and have good leaves too. For the sunny side try Gaura and a small grass such as Deschampsia, this has very airy flowerheads that last well through winter too. Tuck a few little bulbs inbetween for spring interest. Tulipa accuminata is stunning.

tall and wavy is verbena bonariensis.

yes, lovely! I have lots of this. You may also want to grow some chunkier looking plants to offset all the wispiness?

Thank you Volunteer and Seaburngirl. Very helpful suggestions and I will be off to the garden centre as soon as this snow and wind and rain abates. Can you imagine - its almost easter too!