Why all the hullabaloo. If all you fail your MOT on is a B.S mark on your plate the I'd call that a result. I have never had plates with a B.S mark or suppliers address on them and I reckon as long as the font, spacings and the colour is correct then they won't get a second look. Take your car in a month early for it's MOT then if it passes you have 13 months MOT if it fails you have a month to get some new plates.