I was wrong in what I’d thought was on the board but have attached a picture of the unit plus socket. If it’s easiest to call an electrician in then I can do that, just wondered if it was something simple I was missingThat is an MCB, what you need to confirm is - is there either an RCB, or RCBO, providing protection to this circuit which supplies this garage.
Both RCB's and RCBO's will have a tiny button on them marked T or TEST - An MCB does not. An RCBO is an RCD, combined with an MCB, and with have the test button, plus be marked 6A, 16A, 32A, for its current rating.
An MCB only provides over-load protection, an RCB/RCBO provides a different type of protection, protection for you, against faults.

