Does the light go out when you start the car, then come on and stay on? If it does it should still pass the MOT . If I remember right there are 2 fuses and a relay on the ABS system, 1 fuse in the engine compartment and 1 in the fusebox in the car, it might be worth taking these out for a few minutes, this may reset the ABS memory/ self test system, if not maybe a trip to the Dealer, mind you I took mine in and they said it was an unknown code,told me they had cleaned the sensors of grease and charged me £15, it didnt make any difference though grrrr !!