Help me outfox my neighbours! Planning Permission related....

[Fatbergs]

My neighbour told me this afternon that he is applying for planning permission for an extension, which would run along the width of our house at the back. We have a very shallow plot with a long wide house, so this would have a pretty big impact on our north facing kitchen...he called it a "substantial" extension so I am assuming 2 storeys.

To make things even more frustrating, we've only just finished (ie the internal doors are going in next week!) our garage conversion which was of course, hugely stressful and expensive, and the thought of anybody waltzing along and taking away our privacy/market value (sorry, it matters to us) has me, frankly, feeling a bit SICK.

So far, plans have not been submitted - I want to know what we can do other than planting leylandii or whatnot. I want to keep them away from my bounday - how can I manage this? What can I do to get the PP turned down? We are already really overlooked from the side (anything get oked around here it think) and I hate it, I really will want to move of that happens along the back of the house.

Please see diagram below:

house
house
house newbit newbit newbit Driveway

888888888TREES8888888
my garden###########

lounge .... prettynewkitchen
lounge hall sittingroom
------------
@@@@@@@@@ - these are roses

Driveway

You need to have proper information before anyone can answer this question - you don't even seem to know for sure whether this is a 1 or 2 storey building, and you don't say whether you're in a semi/detached/terrace or what.

I think it's highly unlikely that planners would green-light an 8 metre 2-storey extension along a boundary of a semi-detached. In a detached house, where there's a substantial amount of garden between the homes, it would be a different matter. Your neighbour does have some rights to develop along the boundary under permitted development, but you still have a right to light and to privacy.