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

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.

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.

Can anyone help? We are building a 3m extension with floor to ceiling glass doors (2.5m high x 8m wide). I have been warned the room could overheart and we need an opening skylight , but they are expensive. The house is east facing - can anyone tell me if this is necessary please?