Thanks for your sensible replies, I like the bit about having a friendly MOT station, although they often are garages and will want some other work like servicing to get to know me,(I use an enthusiast mate to do my servicing).
Interesting about the cat, because, firstly, on mine there's no bulge and heat shield, but as I say, there's this cert for models up to 2008, and they were sold as 'road legal'.
It must be that, as you say, they don't test emissions so it ain't a problem.
I also have a Harley sportster that I bought the Akrapovic slip ons for, and they DO have a bulge and a heat shield, and they DO have the homologation certificate up to date, so if I'm stopped in France, Germany or Spain, there's nothing the old bill can do.
I'm not likely to go abroad on my XT luckily, love it as I do, I wouldn't make it even if the bike did, having done Spain recently two-up on the Harley, I think once is all I could take.