Best bet is to get a cat and have your exhaust cut and moddified so that the is a section that can be removed and a cat bolted in for mot time.

I had this done on another car, basically they cut out a section and weld on end joints at either end so it can be removed, and a cat bolted in. Cost me £50 cashy cashy at a place in coventry that build stainless exhausts.

Or get really pally with an MOT station or offer some cashy cashy to get it passed.