A north facing bank isn't neccesarily a great problem, Shirley, provided that it gets some sun. Plants for your lime environment could include Dryas octopetala (Mountain Avens) a spreader or the 'silver' saxifrages. Why not visit Tadham Alpines, near Cheddar, and ask their advice. https://www.tadhamalpines.co.uk/
I don't know this nursery, just taken their address from the web. Plants from just about any nursery will be better quality than from a garden centre and often cheaper!

Thank you soo much I`ve never heard of this nursery so will seek it out.

Check out "Rockery Garden Ideas" under 'R" below.

Thanks what a wonderful lot you are X