@christopherblowers any wall / part of a wall that straddles or touches a property boundary, external or internal, is a "party wall" and work on those beyond notional (that is, significantly more than putting dowels and nails in) must notify the neighbour. They cannot object but for extensive work, they can request you to pay for a survey (to record the condition, in case the build causes them damage). If they're OK with it then they can just consent to the notice and you're fine - keep both the notice and their written consent with the property documentation. As Tariq says for small things like this you can find the notice forms on the Internet and send them yourself.

You cannot do the necessary internal works ie drains, ceilings, moving or changing walls, electrics, some plumbing on a leasehold property without permission from the Freeholder, so No is the answer. You are very limited with what you can do to a Leasehold property. You are best to wait for the Freehold Title, meanwhile put in for your planning permission which will be given with ample time to carry out the said works after you get your Freehold. Remember that even though you have planning you still have to have Building Control notices for certain work too.

Hi, Permitted development rights don’t start afresh with each new extension, they apply to every structure added onto the original building. So if you’ve built a large side-to-rear, it’s likely you’ve already used up most of your given allowance. This means your conservatory will most likely require a full planning application. In the event you still have some of your permitted development rights to play with, we would still recommend covering your back and applying for a Lawful Development Certificate. This documentation basically proves to both your local authority and future buyers that your build was legal at the point of construction. Essential going ahead with a second structure. Because you’ll be navigating a more intricate form of planning, we would recommend getting an architect on board for your conservatory. They’ll be able to assess whether or not you can create the structure you want with your remaining allowance, and if not, an architect’s planning support helps you avoid any of the common causes for rejection. If you’d like one of our experts to assess your future plans, we offer free consultations, which you can book here: https://resi.co.uk/advice_calls/new Hope this helps!

In planning terms there is a 45 dec rule i.e draw a 45 dec horizontal line from the centre of the nearest first floor window of your neighbors house towards your house and your first floor extension should not pass this line