Knocking things down

[HJW11]

Anyone had any outbuildings/ outdoor toilets,etc demolished in recent years? I'm considering knocking down an old brick built single skinned building that is attached to the house and shared with next door. It hasn't ever been an outdoor toilet, but is a similar type of building. Obviously if I get my half knocked down, their half of the roof would need replacing too. Trying to get an idea of cost to have the work done, ie 100s, 1000s, 10000s and anything else I might have to take into consideration as building/ renovation work is totally new to me. The plan from there forward would be to install patio doors at the back, where currently there isn't really room because of the way the outbuilding sits. I should stop watching home refurb programmes and getting ideas I have no idea how to execute. Help!

You'll likely need party wall agreement.
Might be worth asking them, if they don't use theirs, if they are interested in gaining extra space by demolishing their one too?

Ooh thanks, @AwkwardPaws27 I did know about that somewhere in the back of my mind. Unfortunately I think next door do use theirs as their garage currently has huge hole in the roof so they had to empty that. Definitely worth asking in case they plan it in the future. Any ideas on cost if it was the whole thing? It is maybe only 2 m by 3 m max including both halves, so not a massive job, I wouldn't think?

No idea on cost, you'd need to get 3 quotes from builders I'd think - I just had to read up a bit on party wall (in our case for a potential chimney breast removal).