I agree with Tani - asking your planning officer is the best way to check what is possible in your particular circumstance. If you have had planning approval then you will have the name of the case officer who dealt with it - that is the best person for you to talk to, as they will already know your project. For your legal situation on the freeholder side then you need to check your title deeds. You should be able to get a copy of these from the land registry if you can't find your own copy. Alternatively speak with your conveyancing solicitors who might have some information stored from your purchase, or be able to advise you.

I have three of these in a loft--side-by-side and quite large. Besides the summer sun baking in, my furniture was beginning to fade. The cost of blinds was pretty steep, so I opted to use light-cream drapery panels with a rod pocket sewn into both ends and thin tension rods to hold them taut. Works like a charm! I still have plenty of light--a softer, diffused light. And the light fabric reflects most of the heat. Plus, the UV damage has stopped. Another bonus--the fabric acts as an insulator in winter so there's much less radiant cold off the glass. A win-win, and the whole arrangement cost less than $100.

I would go forna bespoke piece to armimate the space . Perhaps a bespoke fitting mounted on the full-height wall ??

What do you mean sitting on the roof? Does it have an upstand? Is it on a tilt to let water run off. We have two glass skylights in our flat roof but they do not sit directly on the glass, the builders built an upstand about 25cm high and then the glass sits on top of that. And the glass is double glazed and in a frame to protect it. And it’s on a tilt. What you’re describing, if I’ve understood correctly, sounds like a bodge. A leaky bodge. Do you have a picture?