Where To Start Or End?

I am in need of advice, my partner is a weed addict who is "trying to cut down" again. He's tried twice already since I've been with him in our 18 month relationship. It starts as I promise I'll quit one day. And "I know, I will cut down" he has one day without and gives in buys some more then says "here you have it I'm only having one a night no matter what don't give it to me" yesterday was day three of this so called giving up and a customer annoyed him so he comes home and says "I'm rolling one I don't care", Bad day equals two spliffs, not a lot but not my point. We've come home early from weekends away only for him to buy more just before we get home regardless of it being some stupid time at night, he's woken up so aggressive that he's gone out in the early hours to get it. And I get the excuses of my life is so stressful,we don't do anything, everything is so boring or he gets stressed or angry and its " no wonder I smoke it so much" if he gets angry it's my fault for everything. I currently have no job but have been offered one and awaiting my new start there. But he wants us to save for our own place as we live with his mum n her weed smoking husband. How can I save if he doesn't do the same. He's bought needless expensive stuff to "make money" over the time together. It doesn't work. We have a Black Friday here where when it's payday he'll go ape because his bills need to be paid and he gets left with about 20 a week which goes on weed. So much so I've been left standing in the middle of the bedroom naked while he upends the bed and throws everything around the room to find the keys he threw in a temper. Or when he threw a tv across the room and smashed it all on another Black Friday. Or any tips or extra he gets weed first. I've tried sitting down with him when calm and he says he understands etc and ten minutes later he'll be rolling one up. He says all he needs is our own place and it will be stress free etc but I'll be honest I can't see it happening because all I see is an empty home with him smoking. I cry most days, I've lost all pride in my appearance I just feel so down and I have no friends I never did since moving to devon 7 years ago. He says there is no help he can get. I pay my bills on time and have a pony I CAN afford. I get that thrown back in my face with every argument. So that's just some,is there any help at all out there? Anyone in something similar?
From your description, your boyfriend appears to have an immature view of life. He wants things, Black Friday things/a place of his own, but doesn't have the self-discipline to make it happen.

He also doesn't appear to take any responsibility for his own actions. ( You make me mad, customers annoy me, I'm stressed, I'm bored, etc.) Everything is always someone else's fault.

Pot smoking aside, he has some issues that are not making his adult life very successful. Are you sure this is the person for you in the long run?

Anger issues seem to be real too. Throwing TVs and upending beds is not the way adults handle frustration. I'd be careful he doesn't put his hands on you one day.

Sorry this sounds harsh, but from an impartial view, he sounds like someone ill equipped to handle the day to day decisions and consequences we all must face. Think about what you want a relationship to look like. Does he fit the bill? Are you happy with the way things are right now, because the future could be more of the same.

You seem responsible in your life. You need to think about where you want to be in 5 or 10 years. Is he going to be a help in realizing your dreams, or a hindrance?