Just had mine done and the garage tested it under the new testing process and it went through with no issues. From what I hear a lot of garages are already testing to the new rules but I guess they can't fail you on the new rules yet.
Got to say the thing that would be worrying me more than anything is if you fail a major then the car can't go back on the road even if you are a month early. Its a £2500 fine so would need to be fixed at the garage or towed back with all 4 wheels off the road. Not too much of an issue as I have a trailer but I can see it being an issue for some
Our 40+ year old cars will go through an MOT every other year I think. If you choose not to MOT a historic vehicle but drive it in such a state that it would fail an MOT then its 9 points and a fine. I do take really good care of my cars but I find that the MOT just gives piece of mind and I am not sure that I agree with 40 years being enough that you can presume that all the cars in the age are looked after well and not bodged