You can cover it up / fibreglass etc, but that is just so the MOT man doesn't see it. It would be a bodge. The only way to fix it legally is welding if its weak and structural.

However word of warning ... it could be much worse than it looks.

yeah i know, my mechanic was sure to make it clear to me that it was only a temporary solution for mot time and to stop it getting worse until i get the work done properly..... his opinion was that it was not a structual problem at the moment and this "bodge" was only to keep it from getting worse in the short term and to avoid giving the mot guy anything to "get exited about"

im already looking up good body shops as im well aware that its best to get these things sorted sooner rather than later.

1. It's bigger than it looks.
2. It is in a failure area.

3. Get FILLER and COLOUR MATCH to bog it up invisibly.
4. Once bogged up and sprayed -> GET IT DIRTY.
5. Pass MOT

Last MOT the tested said "yeah, legally we're not allowed to touch any of your own welds. It's more discression that we let it pass". Try filler, tell them weldorz are underneath