Thanks - gone for velum dome style roof lights in the end, so will have all guarantees etc, advice appreciated.

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.

We will have a 2.8m ceiling and Westin have advised their Stratus ceiling extractor would work - in fact they don't set a height limit just say it should be set at the highest point in the room. Might work for you? We also have two skylights but our other one runs the other way so as to best allow light into the internal seating area (where your utility is) - so ours won't match at all! if you want symmetry though, why not push your other one over to the side as well- wouldmake lighting the dining table easier!

Could you use the "Solatube" system? Then the hole for the skylight would have a minimal effect on your ability to use your roof deck.