It is now harder (but not impossible) to carry out major alterations (things requiring a [u]building warrant [/u]and do the electrical works on a DIY basis.
Info (on Scotland)
You should use a competent person for the work, links below
http://www.sbsa.gov.uk/register/SearchC ... ction&ID=2
In England and Wales:
The word from the councils:
http://www.north-ayrshire.gov.uk/na/Bui ... tLevel=3||
http://www.east-ayrshire.gov.uk/devser/ ... ncecei.pdf