The best laid plans...
Permission to Change Your own Home
Some roads have not changed for a hundred years, and won't change for another hundred.
New Planning Rules (1 October 2008) Planning regulations date back to legislation from 1948 and have been revised many times since.
Minor alterations generally require no permission at all—to your freehold house! If you want to fiddle with your flat, read your lease.

This erstwhile mill is now residential.
Development within a single family house is also freely permitted. But external changes - additions and extensions - may require permission if they are substantial.
In addition, authorisation may be needed from the Building Control Department. Your project may be okay in terms of planning but may require other permits.
Is your property listed or part of a terrace? Do you live in a conservation area? An Area of Outstanding Natural Beauty or a National Park?
If yes, additional rules apply.
Loft Extension, Anyone?
The rules for loft extensions differ according to house type:
For more information on planning rules as of 1 October 2008, the government's planning portal has specific information and a page featuring an interactive pop-up house guide.