networkn:
I quite like this. Don't like the lack of a bedside table or even an option to put a book or anything, charge your phone etc.
You can get clip on shelves for loft beds (and top bunks). Intended for alarm/radios and a book. Littlest Miss MDF and I made one for her loft bed. We also installed a downlight high on the wall above her head for reading and that kind of covered everything.
On the bed under window vs heatpump, I've already shown my hand here but I'd go for window (my bed is currently under a window). Double glazing is obviously really helpful but a thermal blind would also be good - the honeycomb ones have a pretty high insulting value I believe.