It is not an easy answer. But, if you are re-roofing the whole property or more than a quarter of your roof, then you will need to submit a Building Regulations application form to your local council. They will advise you on what you will need to do so you can rest assured that you’re following all regulations and procedures.
Bear in mind, that your local Council may forbid the change of a particular roofing material like local stone, local slate or thatching for a modern material (especially if the project is to happen in the conservation area).
So, keeping it simple, you do not normally need to apply for planning permission to re-roof your house or to insert roof lights or skylights as long as your project meets the following conditions: