MOT fail Body Mountings

Well took my old 90 for its MOT Friday and it failed on a few things, not to bad but one of them is :

On the MOT it states ( mounting point forward of the rear wheels both sides ) body or chassis has excessive corrosion, seriously affecting its strength within 30cm of body mountings [6.1.3]

Any advise on the best way to repair this ?

I'd get some sheet ally ( same thickness or a little thicker ) , cut out the corroded bit and bolt the ally plate to the body and the mount .

I replaced the whole floor in 3mm chequer plate using the original bits as a pattern.