Not all elements of building work require Planning Permission.
Works to doors and windows can be some of those, www.planningportal.co.uk says:
"You do not usually need to apply for planning permission for:
New roof lights or skylights will not normally require an application for planning permission providing:
Also, if you are a leaseholder, you may first need to get permission from your landlord or management company".
Reference take from: https://www.planningportal.co.uk/info/200130/common_projects/14/doors_and_windows
YourBuildPlans supply a building plans service to Builders and Building Companies across the UK.