We have found a useful guide published by Hager regarding installing consumer units.

This guide will help you understand the Wiring Regulations and current Building Regulations, providing the necessary facts to construct compliant installations including Consumer Units.

The PDF can be found here – http://www.hager.co.uk/files/download/0/2802_1/0/Hager%20Guide%20to%2017th%20Edition%20Consumer%20Units.pdf