Will there be enough light beneath the surface to take good photographs?

That depends on how close you are to the surface and of what you are taking a photograph of.  When you are still relatively close to the surface in photic zone, you will have decent light for underwater photography.  However, that will also depend on whether it is a cloudy day or whether you are taking a photograph of a fish that is hiding amongst the rocks.  Once you dive deeper the light will fail and it will be necessary to have an external flash in order to capture good images.