Technically you should not change lamps to LEDs unless the fitting was designed for LEDs.
When it comes to MOT Test time the inspector is supposed to check that correct bulbs are fitted. It is a moot point if a fail would be given for rear/side lights but I would hope that headlight modifications would attract a fail as I'm heartily fed up with being dazzled by drivers with modified and thus poorly focused directed lights.
Fuller details in this post Got some led headlamp bulbs coming
When it comes to MOT Test time the inspector is supposed to check that correct bulbs are fitted. It is a moot point if a fail would be given for rear/side lights but I would hope that headlight modifications would attract a fail as I'm heartily fed up with being dazzled by drivers with modified and thus poorly focused directed lights.
Fuller details in this post Got some led headlamp bulbs coming