How to avoid LDR controlled light self-latching?
Instead of the LDR, you could use an infrared-sensitive phototransistor.  The IR phototransistor will detect incandescent light, but not (most) LEDs.  Fluorescent lights and household LED lights also don't put out much IR, so this won't work if you have these.

I do suggest that you add some positive feedback (hysteresis) in your circuit.  As it is, the FET will find itself sometimes biased in the linear region and not operating as a low-loss ON/OFF switch.  Instead, it will heat up and possibly burst into flames (depending on the load and the power source).