A solution to the light and the MOT inspection would be removal of the offending instrument cluster light. If you have no codes the MOT inspector won't see a light and can't find a code; A solution for your situation, but the problem would still be there.
There have now been several post on the forum with warning light on, but no codes. Hopefully someone will find a fix soon. I'm, beginning to think the problem may actually be in the instrument cluster.