[Dave]

Notice the difference between the last shot above , where trying to get intermediate exposure has meant a dark interior & over exposed shot out of the window. See why shot 1 of the garden room now works so much better with Photomatix

I think your focal range of your kit lens is fine for the job. If you want a bit extra quality in the shot then look at the Nikon 18-70mm kit lens, or even the Sigma 18-50mm f/2.8 which will be better for this light