The 'freewheeling' diode is only needed when the load is inductive. An inductor produces a voltage back into the circuit when the current through it is turned off and that is what the diode protects against. A filament lamp or LED do not produce a voltage back so the diode isn't needed.
Otherwise the circuit is correct. The load will turn off if the input voltage is +12V and it will turn on when it is lower than about +11.4V.
Just be careful if the load is ONLY an LED as they do not inherently limit their own current, a series resistor would be required. A filament lamp regulates it's own current as it's resistance increases with temperature.
Brian.