Received letter from council re proposed extention next door (semi)

[20questions]

Hi - as above. Proposed single storey rear extension to next door semi (new neighbours!).
Reads "Single storey rear extension with depth 5 metres from original rear wall, eaves height of 3 metres and a maximum height of 3.2 metres. Council must make a decision as to whether permission from the council (prior approval) to build the extension is required by 26th November"
Without wanting to be difficult in any way, I also obviously want to protect my own interests..
Is this a normal height for a single storey?
Do they need to leave a gap between my boundary fence and their extension or can they build it fully across their house width?
Should I have my own party wall surveyor?
Really know nothing about these things!

I think first you need to see the actual plans of the extension. Either ask your neighbours or they should be available on the councils website under 'planning'

@TwoLeftSocksWithHoles Yes - the letter said the plans will be available on their site next week. What should I be looking out for in the plans other than the measurements - really ignorant about these things 🙄
(BTW love your username - think I've got the matching pair lol)

First look at the plans on the council's website. Many councils won't allow extending to the boundary but you would need to check this for yours.

The height seems fine to me.

As for party wall surveyor, I would hold off on this until you find out when they are intending to do the work. No point in worrying about that side of things if work doesn't start in another 2 years.

This isn't a normal planning application. It basically for an extension under permitted development, but because it's a bit bigger they have to go through this prior approval process details here from the planning portal

Ask your neighbours directly what the plans are. Do you have plans to extend in future? You might be able to work together to some extent.

A 5 metre long roof with only 0.2m drop is very flat. Check where the rain is draining. It does sound like the neighbours are going long, but keeping it low. They could go up to 4 metres for the ridge - either where it joins the house or along the boundary line (which would be very high for neighbours)

If you need to object, then this is a useful guide how to: planninglawblog.blogspot.com/p/how-to-object.html

I discovered that my council didn't take 'design' into consideration for these larger permitted development processes (their argument was that the materials match the current house so design is not a consideration). Also windows up to the 4m height of a 'single' story don't need to be opaque. Not nice for neighbours.

I would chat to your neighbours - I am surprised that they have not initiated a conversation with you. If they do not do this then you need to study the plans in depth, make a list of questions, then arrange to go round and have a chat.

Very bad manners from the neighbours not to talk to you before they submitted the application.

Thank you for the info and pointers - it's helping me to understand a little better. I understand that I have been consulted because it's 5 metres so quite a bit over the 3 metres where I presume I wouldn't need to be consulted.. The link above was helpful and also to be mindful of drainage..
Once the plans are online, I'll post them up and hopefully the kind - and much better informed than me - will advise further of anything I should be aware of.
The house has been vacant for around 6 months now - in fact since they bought it! They have done a lot of gutting inside in preparation for a total renovation/extension so I know the building work will be going ahead as soon as they have the relevant permission.
I don't want to be awkward as they are entitled to extend and maximise their investment but obviously want to ensure there won't be any negative impact on my home..