Ive recently created a rockery and I did do a few blogs on it, including the plants that i have put in.
off the top of my head I have the following:
Crocus, Anemone blanda,Iris reticulata, Iris histroides, Phlox sublata, several small Primula, Dianthus, Haberlea, Hepatic nobilis, Aubretia, Sedum spurium, Pulsitilla and several small narcisus such as tete et tete.

If you go to the bottom of the page you will find the alphabet. click on R then find rockery and then that will open up all the information from other members.

welcome to GoY too.

I like the selection suggested by Seaburngirl but note the accidental ommision of saxifrage, there is a huge range of these in the garden centers. For early summer colour you could use Fairy Foxglove (Erinus alpinus) a small, pink flowered plant that self seeds a lot - these make great colour over the rockery and excess seedlings are easily pulled out. For late summer you might use the late flowering gentians.

ooh yes saxifraga, I have a few in there. :o)

Thank you so much Seaburngil and Bulbaholic - this gives me an excellent starting point - I'll be doing some research today and looking at your suggestions - a much appreciated guide for this novice! My garden is about 50m long so we are going to tackle it in sections.