I wouldn't think the legality is an issue, but there shouldn't be a problem with the MOT.
When I had my last one, I was asking about removing the rear indicators and just using the front bar end ones. The MOT station weren't sure so they rang their local office and were told as long as you have indicators fitted which are visible from the front and rear then that's OK
There is an MOT website you can check but it's very vague and non-committal
