I've just had a quick check in my car. When I turn my ignition on the traction control light comes on, then after about a second or so, it goes off. I'm guessing that will be an easy way of knowing whether its something like a blown bulb?
On mine, its a yellow light, with a triangular warning symbol in the middle, with an incomplete circle round it and one end having an arrow point. Its the centre bottom of the light cluster, although that may be different with your car.
I'm also able to disable it without turning the ignition on, although again this may be a subtle difference between TC and ESP...