On the lebbenfiddy there's an adjuster bolt under the lever and you'd need to adjust the wee pushrod too. I should imagine that the 12 is quite similar too Ricky.
when adjusting the pushrod that is connected between the master cylinder and lever, MAKE SURE YOU LEAVE SOME FREE PLAY ! otherwise you will give yourself serious problems with the rear brakes binding on.
if in doubt, seek help from a mechanic.
I fitted one of the brake pedal enlargers on mine - which admitedly only lifts it by the width of the metal it's made of - but because it is wider I no longer feel like it's too low or that I need to search for it.