If you put an LED on the output of the module, it will be light up normally. When you point your 38kHz IR signal at the receiver module, the LED will go dark. So yeah, you are all set. Replace the LED, with a driver (transistor) suitable for your relay. One other note, the receiver modules usually have an AGC (automatic-gain-control), so you might get shorter range. More circuitry would only send burst of the 38kHz signal, and after the receiver you would check to see if you are missing pulses. For your range, shouldn't matter though. I don't know if the receiver can drive a relay directly, don't think it will, unless it's very low power. A GP transistor, resistor, and diode is all that's needed to drive.