I can relate to you in some ways although our situations are slightly different. I haven't been able to finish my sixth form education either and haven't had a job due to mental health problems. I had to leave home at 16 though so now have a flat. It must be very hard for you living at home but it isn't your fault that you haven't been able to finish your education/getting a job. It's clear from your post that you really want to succeed in getting a job and you are doing everything you can but you are unwell and sometimes this gets in the way.
Have you ever spoken to an advisor at Connexions? You can check out their website at
www.connexions-direct.com . I'm with a similar service in Wales and I think it's a great service because they can suggest all different ideas that suit your needs. I recently took part in a course with the Princes' Trust which was called Team Challenge. It was a 12 week course which helps you to learn new skills and something like that might be brilliant for you.
I'm also doing an open university course at the moment just so I can get some qualifications. As green.eyes suggested, how would you feel about doing some qualifications through home studying? For me it's really ideal because I'm too anxious to go out and study at school/college but want to be learning new things.
I've also found volunteering great. It's brilliant as it builds your confidence at work and places are very happy to have you volunteer regardless of qualifications and things. Also, I find because I'm not paid I don't feel like I'm letting them down so much if I absolutely have to call in sick because I'm really low on the day. It's also fab on your CV!
If you want to chat feel free to add me to MSN or PM me,
Lotti x