ELECTRICAL work in the bathroom should rarely be attempted by DIYers – you may be breaking building regulations, as a bathroom is regarded as a ‘special location’ for electrical installations.
Play safe and use a qualified and reputable electrician who will make sure the work’s safe and legal.
Although you can employ a building control inspector from the local council or a private firm, the easiest option is to use an electrician who belongs to a ‘competent person scheme’, such as NICEIC (niceic. com).
They can self-certify that their work complies with building regs and should provide the completion certificate you need.