Spot on Arran
One thing to remember is that ifthe render somes out "blotchey" then increase the number of samples in the ambient occlusion node that you created.
The standard preview render, I think is not really for doing much, it only contains the standard default light and the lambert shader, its more for when you strat to add textures and lights so that you can see whats what so to speak.
"No pressure, no diamonds" Thomas Carlyle