Is the circuit giving on codeproject.com site able to give the feed back that whether the device switched on or not?
No, that one just controls the device, there is no feedback to see if power is actually applied.
A very simple idea... use another LDR and whatever circuit you already have devised for it, connect an old-fashioned neon panel indicator light across your mains power lines that you want to monitor, and put them both in a bit of tubing at opposite ends to block out ambient light. Simples!
Well, nearly simples... you will need to 'buffer' the output of the LDR beacuse its resistance will vary with the AC. Just use a reservoir capacitor in your circuit for that. You could also use a phototransistor instead of an LDR, but if you already have a design for using an LDR, that's fine. Basically, you are making yourself an optocoupler.
I don''t know off the top of my head what current a neon panel light draws, but it won't be much and probably a lot less that even a capacitor power supply. If you get one from a supplier, it should tell you the power requirement. I think it's generally one mA or less.
Don't forget that a neon indicator light needs a series resistor to limit current, suitable for whatever mains voltage you have. A full panel light will usually have one inside already, but if you get just the bare neon bulb, you'll need to add a series resistor.
A neon indicator:
Link.