Just seen pictures . Fault 1 flue is too close to air vent, if bricks are 73 or 65mm the did stance is less than 300mm. Page 6 of boiler guide I think? Distance to opening or vent from a flue.
Fault 2 no eath on meter outlet.
Fault 3 flue looks to be poorly fitted into boiler and not sealed to brickwork.
Pipe work missing a few clips and it's very close to your electrics but they are less important.
I would anticipate that all ga safe would do is send installer a ncs letter and invite the 'plumber ' to join gas safe.
The flue and thermostat will require a gas safe engineer . Earth is a sparks job or qualified gas fitter.
You could remove air brick and replace with bricks or cement it over (looks poor tho)