Well thats a good use for it. Looks very interesting.

The roller blind with sheer curtains will give a soft look and block out the light while you sleep. The floor to ceiling curtains probably won't look as nice due to your small space and the cornice so just above the window and a little wider than the window to make it look larger. The bed head either upholstered or timber needs to be light in colour so it doesn't dominate the room (the timber will be easier to clean) The design of the bedside tables depend on what you use them for but don't have too many items stored on them. The light also depends what you use it for (needs to be more direct if you use it to read). The addition of a large mirror will add the illusion of space and luxury. As you have a large bed in a smaller room just make sure the linen is not dominating the whole room. Good luck :)

Is it possible to get a white or pine bed and paint it?

paint all the walls the same colour, don't forget to finish the cornice and once you add a bedside table and lamp and tidy the curtains the angled wall will just be background