@EL8888
To answer your initial question, No, it's NOT supposed to be this hard.
''The mess, the bellowing down the phone, the lack of organisation with the move, annoying coffee making rituals''
- The mess. He actually does think it's your job to clean up after him
- He really doesn't give a shiny shit if his bellowing bothers either you or the neighbours
-
His 'rituals' must be accommodated by you (But you will never be given the same consideration !)
''The latest revelation this afternoon, is last night he threw away a box of my documents. He decided they were recycling (they weren’t) and they weren’t in the recycling box.''
- You chose the right word when you said ''he decided'', i.e He knew damn well that your 'documents' were yours (and yet he gets to decide what he does with them !!
).
- He also chose to not ask you if your documents were important to you
- He really does think that only his 'opinions' and 'thoughts' matter, to say nothing about his 'possessions'.
- Ask yourself this.......what would his reaction be to you throwing away his things ????
'' Part of me wonders do l want the rest of my life to be like this?''
Nope, you really, really don't want the rest of your life to be like this 
But if you stay with him, then it will be. 
''The prompting and reminding, sorting out of fuck ups etc. Please note these is part of a wider pattern of scattiness, losing things, breaking things etc.''
This, forever.................
''His things are mysteriously always fine'' and that's because he cares about his stuff. (But he won't ever care about you or your stuff)
If it's not too late to pull out of the house move, then I'm with all the PP's who advise you to pull out !