Q.pruning red twig dogwood
Is it too late to prune red twig dogwood, bearing in mind it is now in leaf and flowers will form soon. Also, should I just remove the flowers when they have finished flowering?

The recommended time to prune dogwood is autumn to winter. This article will tell you more: https://www.gardeningknowhow.com/ornamental/trees/dogwood/trimming-dogwood-trees.htm
Also, here is a little more information about red twig dogwood: https://www.gardeningknowhow.com/ornamental/trees/dogwood/red-twig-dogwood-care.htm