Hi mate.
Just wanted to say that I know (almost) exactly what this feels like. I have a 15,000 word dissertation & 10,000 word portfolio due on April 29. I'm massively behind because of my own health struggles (I posted on here a few times about it).
Folks on here urged me to talk to someone, so I did. First my GP and then my uni tutor. It was a massive relief to finally tell someone I was struggling, even though it didn't seem like there was much that I could do. My tutor was very understanding and helped me set mini deadlines to help achieve my goals. If you haven't already, try speaking to your course lecturer. They may be able to offer extensions?
One thing that has definitely helped me has been getting out of the house and heading down to the uni library to work. Can't get anything done in the house because I settle in to that depressing yet oddly comfortable headspace. I can work for hours in the library though. Perhaps this could be of some help to you?
Hope you can sort something out and start to feel better soon!
(P.s. Congrats on trying to give up fags. It'll be tough but totally worth it.)