Having just read the above, I've measured the Amps used on my UK 240v supply at the wall socket.
Standby : ie just Raspberry Pi3 running OctoPi and a charger to a tablet ( charged) - 0.15 Amp
Idle : as above, plus Wanhao i3 v2.1 powered on and ready, extruder fan spinning and two 500mm strips of LED lighting - 0.4 Amp
Full On : as above plus bed heating, extruder heating and both Z axis servos running - 2.0 Amp
After a 4 hour print the maximum recorded Amp's Used was 2.05 Amp.