IIRC, the Demon is a pretty fast actioned rod. 10' #6wt is a useful size and weight of rod, but the Demon
may be a challenge to get to grips with as a beginner. Much depends on the line.
Going afloat on Loch Assynt, a loch I quite like to fish, I would have a 10' #4wt for top of the water use and a 9'6" #6wt or a 10' #7wt set up for bigger/meaner flies on a sinking line.
A 10'#6wt
is a useful all-round size, but there would be some sense in getting an easy-going rod in the 9' range as a starter.
With that said, and to be honest with you, the best investment you can make in the short term is getting some good quality qualified instruction sorted out.
The gear can come later - when you know what to do with it
This might help you find an instructor near to you:
http://www.sgaic.co.uk/SGAIC_find_an_instructor.html#HighlandsH