It seems to me there is more than one thing going on here.
You have no friends to talk to
You have no hobbies
You live in a house share with people you don't like
You refer to work as you go, you come home so It sounds like you don't have job satisfaction?
You have tried the GP and anti-depressants
You have tried social groups
You have tried volunteering
You do not want to try any of these things again
Going to the GP and asking for help is hard, because to get help you have to really push for it and it sounds like at the moment you are in a place where things happen around you and you feel you have no control, and so going to the GP again, may not help because you aren't ready to push for the help and support you need.
I don't believe any one thing will solve all of your problems but I do think it would be good to try and draft a plan. You talk about death as though it is something that will happen to you, not something you will take control of but you need to draw a line mentally about what thoughts are and aren't OK to handle on your own.
Thinking you would gladly take someones cancer is one thing, thinking if you don't look both ways when you cross the road is another. Can I ask you to write down some emergency numbers for the groups people have suggested it here. If your thoughts ever turn to playing an active role in ending your life you will phone for help. Make that decision today that you will do that.
If you can do that, you are starting to take control.
Then move to the next thing.
Is there anything about your job you like, dislike is there a dream job? Do you need to study? We spend a lot of time at work and it's important to try and be happy in what we do. If you like your job, great make an active decision to say, I like my job and I want to be there. If you can't lets look at what you can do to take control and change it. Can you study for free, is there a course that needs paying for - that is an investment in your future, you may meet like minded people, you may not but the class is about getting you a job you want any other interaction is a bonus.
Nothing will be achieved overnight. There will be a long period of time of trying before things seem better but every change you make acknowledge that you have made that decision to improve, remember all the decisions you have made to improve and in time you may work yourself out of the situation you are in, or you may feel stronger to demand help and have enough hope to want the help