Sash Windows - planning and/or regulations

[muffins78]

I've confused myself. If you are having your sashes refurbished e.g painted, draught proofing and maybe double glazing - what do you need?

I understand about FENSA, but if the fitter isn't registered and you are keeping your original frames etc., and the exterior won't change, it's says planning is not needed on Southwark. It mentions direction 4, and when you look T this, it mentions lordship lane and shop frontages etc..

I am not sure then where the regs come into play. Can anyone please help or advise based on their experience? Thank you!