OP
thankyouIf the hole is bigger then that is down to the plasterer or builder for not cutting it correctly, having a gap like I said is not an issue as long as the live terminals are not accessible or exposed when second fixed.
I get the impression this has been a bit of a rocky ride and only having one side of the story means it is difficult to give a overall view but as for the issues we can see then we can give you our professional opinion.
Maybe it is the perspective in the photo but it doesn't come across as been too big a hole but if that is the case then all that needs to be done at this stage is the section of plasterboard to be cut out and a new piece put in with a correctly side socket cutout. A deeper metal box could also be fitted but that is not really a issue tbh.