Considering the large surface areas of the wings of the Boeing 747 and Airbus A380, can the bleed air for deicing the wings be switched on and off as needed and if so, is that automatic and where are the sensors to control this (on which parts and why).
Yes. Automatic operation exists as well (may not be installed/chosen by the operator).
Nitpicking: this bleed air is for anti-ice, not de-ice (but even manufactures get it wrong in the manuals sometimes, see below).
Saving this bleed air when not needed saves fuel and engine wear, and allows higher more efficient cruise altitudes.
Speaking of the A380, due to its thick wing, it does not need much anti-icing.