Fixing a rust patch

[lolsteve]

It's a massive bodge IMO depends how bad it is really

Point taken, would chemical metal be as bodge? I can imagine the roof takes some forces through it while driving but not enough to break the chemical metal bond?

I have a grinder with a few wire heads bit harsh bit will get into the metal deep to get the rust. I have a welder at hand you could come to my unit and we could have a look. Only thing with the heat of weld it can bubble the paint. DIY job witch is a bodega but works is sheet of metal under neath with chemical metal then fill but it's up to you. Get the roof lining out see if it's inside. You have my number any problems give me a text. Could always get the roof wrapped saves painting and it showing it's been done

The chemical metal idea sounds good, same lines as the fiberglass approach i suppose. Welding would be the most secure method but alot to go wrong if welding inside the car and like you say bubble nearby paint.
Cheers though, I'll get poking it and see what the situation is then give you a call if it's going to be a proper shter of a job