The May changes are still only draft so not 100% certain will come into force then , quite common . The test re exhaust ,looks about the same levels havent been changed , they only have to be taken to 50% of max not as some used to be to max governed rpm . Usual wolf calls i think
I cannot conceive that a large proportion of commercial vehicles - the vast majority of which are diesels - are going to be put off the road. Relax, it will be fine apart perhaps from older vehicles in poor condition and they will probably be OK once serviced properly.
DPF's are going to be checked for tampering or removal, either case means failure and possibly a large fine. Plus any visible smoke from a vehicle with one is also a failure, accordingly to the news papers.
A couple of years ago our tester said our MH exhaust was near the emissions limit and that before next test I should give it a good 'blast' on the M/way. So on the way to the test I got up to 60-65 and dropped into 3rd gear for a mile or so. It sailed through the test and I do this each year and have had good results since.
If you do it, just watch the rev counter to ensure not over-revving as you go into third - the speed and gear I have quoted is fine on the 5-speed 2.8jtd, but other engines and gearboxes might be different.