Thanks for your replies.
Your suggestions mainly echo my own thoughts but had not noticed the dust spots, although they are quite obvious to me now. Thought that the moon was the main culprit, but was surprised how much vignetting there was. Don't know why the vignetting is off centre. Could this be collimation?
As for the number of exposures, would have taken more but ran out of time and laptop battery - will have to remedy this next time.
Flat frames - a few questions here. Can I take a flat frame by setting up my laptop with a full white screen and taking a shot of that? Would be easier than creating a lightbox. How do I create an articicial FF?
Still lots of learning curve left methinks.
Regards and Thanks,