A Citroen ZX I had stated in the manual that the airbags and seat belt tensioners should be replaced at 10yrs old. Wonder how many have been doneMy Alfa Spider has a plate on it which says it wants the airbag gas generator checked (how?) when it is ten years old. My MB doesn't give me any instructions!
Warning lights should have no bearing on MOT. They test actuals (like brake efficiency etc). They certainly do NOT test whether the airbags will deploy! The SRS light being on means that the airbags are probably disabled. Fine if nothing hits you, but you do need them fixed for the added protection they give you.
I have no doubt that an airbag saved me from very serious injury a few years ago. Had a burned nose and a broken thumb (standard airbag injuries), but it definitely would have been worse without it... Get it fixed, even though the MOT won't care about it!