Bullet, best idea ever!
Will, come to think of it, there is! pop off the wheel arch liner on passenger side, look below the headlamp and theres a big bottle full of washer fluid with what iirc looks like a motor attached too it and an electrical connector.
mines already dead, im guessing motor is dead as i cant wash my lights (and it upsets me that this is broken) but you could just unplug this. Just remember to re-activate it come MOT time.
I have yet to find a fuse for the washers as that was what i intially suspected was wrong with mine!