You would totally benefit from an "L" shaped glass desk like I have (that way you have one side of it against the window, and the other towards the TV), but goes a bit outside your budget ^^' Also considering some kind of painting (they're getting really good now in the sense that you don't need a million coats and they usually come with primer mixed in) would be an awesome idea too, would totally be fantastic to do some kind of multi-tone kind of thing (the actual roof a cool colour like grey or lime-green then the actual "wall" the opposite).
So something like a 125-150 pound budget could work wonders for you!
P.s. I was in Scotland few weeks ago for vacation, was constantly raining. So I'm surprised at the snow hah
P.p.s I remember telling myself that if I ever had an attic space, I would do this thing I once saw which involved installing rock climbing rocks on the ceiling. Looks amaaaaazing haha