Nick, this whole place is populated by the strange... its just that some of us are stranger than others
I don't see why you cannot usefully turn that space into a covered, protected area for growing.Has to be better than a junk collecing space (and I know lots about
that sort of problem, though we recently did fill a large skip in the course of a clean up .... she said, blushing with the pleasure of that rare achievment!)
I don't know that it would need to be fully enclosed.... often times just keeping the rain off is more than enough for some plants. Depends what you might want to grow there. I think it would make a good home for a range of alpines and little bulbs. Maybe need some careful shading in the summer if you get "proper" summer sun on it!