Some domestic electrical work in England & Wales is 'notifiable' and must be signed off.
Part P of the Building Regulations covers electrical safety in dwellings in England and Wales.
Notifiable work includes installing a new circuit, work in a bathroom or shower room zone, and consumer unit replacement. Adding a socket or light to an existing circuit outside special locations is usually NOT notifiable.
You have two legal routes for notifiable work: use an electrician registered with a competent person scheme (NICEIC, NAPIT, etc.) who self-certifies, or notify your local authority Building Control BEFORE starting and pay for inspection.
Getting this wrong can mean enforcement action and real trouble selling your home — buyers' solicitors ask for the certificates.
This is guidance, not legal advice — always check with your local Building Control before starting work.