Their are no MOT regulations regarding different springs between the front and back axles.
The criteria it will have to pass for MOT is that:
They are the same accross the axle (i.e both fronts the same)
They are not cracked or broken.
They do not dislocate from their mountings when the vehicle is raised off the ground.
That they actually upport the weight of the car. (i.e the car's weight is not sitting on the bump stops imstead of the springs).
As long as they do the above, they will pass an MOT
