so as above my hand brake light is always on, hand brake up hand brake down it just wont bugger off! EXCEPT ...when braking reasonably hard and it goes out?! then as the car comes to a complete stop it comes back on

so iv started looking in to this and my first check was the switch under the hand brake itself. i managed to use a long implement (stereo key) to fully depress the switch and let it return a few times but it stayed one HOWEVER i did notice it gets dimmer and brighter as i turn it on and off..so my question is ( sorry about the essay) what else would be holding the hand brake on? could this also have something to do with my brake judder?
any help or advice would be much appreciated