In short terms yes, but they need to be registered as a competent electrician.
Depending on the works they are carrying out there work must be tested and certified by them or a 3rd party.
If its a 3rd party (IE Building control) the officer must check the 1st fix (all cable conditions) this is before any plasterboard or plaster is used to cover cables. Then the officer must check 2nd and 3rd fix before anything is singed off.
Remember any new circuits IE hobs / ovens need to be notified to the local building control along with any alterations done electrically in the bathroom
If in doubt contact a local / registered electrician for advise on what works can be done.
