No Wayne, it isn't. The Sun (and others on a slow news day) would like you to believe that but it just ain't true. Read the gov site here:-
https://www.gov.uk/government/news/mot-changes-20-may-2018
There is no good reason for a diesel cycle engine to be "less clean" than a petrol one. Participate emissions are almost always stopped by correctly adjusting the vehicle's fuel pump. No real need for a filter. And the Nitrous Oxide thing can be stopped by using slightly different fuel which the fuel companies could put out but don't. Running the diesel cycle on veg oil would work for example. The components for the "nasties" come from the fuel remember. And diesel engines are more fuel efficient too, using less diesel fuel per mile than a petrol one, thereby conserving precious resources.
Surry Bob, are you serious when you say"We're pretty good on roadworthiness over here. Do we really need their [EU] "help" or are we not able to set our own MOT standards?"
Our current MOT may have been sufficient when I was driving an Austin Allegro, but it certainly isn't now.
And finally, if you're worried about your car failing, then why not get the MOT done a couple of weeks before it's due? Then if there's a problem you've got breathing/arguing space.