Damn that is very unlucky! On or after Aug 92 is indeed the cutoff point for cars with cats so you're scuppered on that front, only hope is finding an mot station that will test it as an earlier car, but with all the computerised stuff i dont know how easy that would be. The other thing you could do if you wanted it to pass legitamently, you could swap in an engine from an older car. The test is on the car or engine, whichever is older. but you have to prove the engine is older to the mot station:
http://www.motuk.co.uk/manual_730.htmWhat you might possibly be able to do, is get on the phone to VW, with your engine number. Get them to send you documents that show exactly when your engine was made. If it is before aug 92 (which it must be, cant have built the car on the day it was registered

) then this i think would be enough to get you through the test. Try your dealer 1st but generally they're a bit useless, there are some exceptions but the main UK HQ would be a better place to start calling

although it does say cars fitted with a
different engine, so technically this shouldn't work. Worth a look into anyway!