sounds to be broken tbh.

u have turned the power back on havnt you?
try putting both the cables in one side of the switch and turn the power on just to make sure the bulb aint blown or anything.

i dunno about the touch senstive fancy ones, but in general they r pretty much a variable resistor.

so if the lamp comes on when u put the 2 cables together and not through the switch, after reading the instructions to make sure u aint gotta do anything special i'd be going back to b&q for a new one