230V AC triac dimmer for single phase motor and LED lightbulbs
I would have drawn R4 and C3 below Q1 , but yes that is a correct layout.
it probably won't work well with LED lighting, because LEDs will respond do the tiny currents that the snubber leaks through. This can be mitigated by adding a load in parallel with the LEDs,  a lighting capacitor could be used here.