hi Jill, as Barry said, the commanding setting in the camera can set off the 800, but, i feel, an off camera flas is required when you do not want light directly at the shot, this is where i'd personally use a Nikon SC-29 cord. this connects to the hotshoe like the flash would then to the flash, giving lots of movability.. and i think jessops do their own cheaper version.
but id like to see results from Barrys 35mm "diffuse" idea

J