The MOT requirements are there must be a functioning tell-tale for turn signal operation, but this can be audible or visual. If both and one fails it's still an MOT pass if the tester can see or hear the other. Hazards must have either a dedicated visual tell-tale or both turn signal visual tell-tales flashing together.
I found I needed a louder audible warning on my Roadster though as the OE one is feeble.
