We cannot give definitive guidance on whether you will need planning permission for
your project- some items of permitted development. Even if you believe your proposal
is permitted, it would be wise to check this with your local planning department-,
and if you need proof your work is allowed, they should be able to provide you with
a lawful development certificate (LDC).
You need to make sure that you aren’t in breach of the Party Wall Act when building
near a neighbours property- or even altering your own. The costs involved in a dispute
could be high so its best to check this out.