The simple way would be to use a 18m2 Picaxe chip as these come with the option of using "touch" sensors within the program commands. (up to 10 sensors)
You would also need a transistor driving a relay to do the AC switching, other than that a 5 volt supply for the picaxe is all that would be needed.
The touch sensor can be any metal plate you can attach a wire to, and the plate needs a plastic insulator coating over it, or a good coat of clear enemal would work too.
The touch sensitivity and reaction time can be set in program to suit the application.