Brake lights come on when Clutch Pedal is pressed ?

I own a 2001 Picasso, when i put my clutch in the brake lights come on, after looking on the net its seems like the cause is the sensors which active the lights once the correct pedal is pressed.
It seems i'll have to get access to the switches but havent got a clue how to go about this as i rarely go under the bonnet, could anyone help and let me know how to correct this problem and hopefully save a trip to the garage.
Any help would be really appreciated.