Sandy, for a first time effort, just keep your exposures short, until you get the hang of it, and seeing that your set-up is not Auto Guiding at the moment, I would no exceed 60secs, unless you have perfect polar alignment.
Just leave the camera on AWB, it will look after it for you, you can always fiddle with that sort of stuff when you get more experienced.
ISO speed, stay around 400, if your skies are pretty polluted.
Your scope is F/4.5, so it is reasonably fast, the main thing to do is enjoy, and have fun, that is what it is all about, Imaging can be a night mare, but it is fun learning.
Just have a look at my Deep Space attempt of the Helix
Leon