So I guess you now have that warm smug feeling that you have a RRC WITH an MOT

. I'll say it anyway - I know how you feel.
Guess if you got through MOT ABS is O.K. Checking wheel bearings is easy, jack up to lift wheel, grab wheel top and bottom and rock it backwards and forward, if movement, bearing needs adjustment. BUT if you got through MOT, unlikely to be bearing as this would have been checked.
Not sure that there is anything to go wrong with an exciter ring - it's just a piece of metal bolted to the inside of the rear hub or in the case of the front wheels, it is the outside of the CV joint. Hey ho, chin up and prepare for the next hissy fit your Rangey throws - trust me it will, sooner or later