Could I have some ideas for bright coloyred plants to go in my rockery please

You could go to the library and borrow a book on rock gardens. That will give you a long list of plants.

Additionally, there's over 200 rockery photos on this website. Just scroll down, click in "R" then "Rockery Ideas"

then there are lots of bulbs to consider too.

Rockery plants vary considerably in size - for example, Phlox subulata is lovely but can spread up to a metre wide; Aubretia for Spring, then Lewisia, Nemesia, Saxifrage, Lithodora and many alpines.