1. Check registration
For any notifiable work, use an electrician registered with a competent-person scheme such as NICEIC or NAPIT. They can self-certify the job, which saves a separate building-control fee and gives you a valid certificate.
2. Confirm certification and insurance
Make sure the quote includes the relevant certificate (for example an Electrical Installation Certificate, or an EICR for an inspection) and ask for proof of public liability insurance.
3. Get it itemised and keep the paperwork
Ask for labour and materials separately and a clear scope. When the work is done, keep the certificate β you will need it when selling or renting the property, and for insurance.