that when you press your foot on the brake that the pedal
does not travel all the way to the floor and also that
it does not contine to creep down when holding your foot
on the pedal. This would indicate a leak in the system
and needs to be repaired, before driving, for safety and
not just to pass an MOT!
Excess travel in the pedal can be caused by lack of adjustment
(Drum brakes) or worn Pads or disks. These can be checked later
in external checks with the wheel off if necessary.