I hope you don't think I was having a dig with my last post... its hard for most people out there, my works very rough at the moment, we only switched on the heating last week, and even then it was just to stop the flat going lower than 15*C, and only when we are in. All our food is value or reduced. It just seemed a bit odd that you PM'd me about buying my Panda 4x4, and here your saying you've been out of work for 12 months and can hardly afford to eat!
If you've gone through 12 months of having 2 interviews a week, either the job centre is sending you to the wrong jobs (which wouldn't surprise me), or you need to brush up on your interview techniques!
There should be a few 'interview technique' books at your local library... its always worth reading through them, you might find you are giving the wrong answers or impressions...
As said, volunteer work is often a good foot in the door, as is offering to work a few days for nothing, to show you are a good worker and hopefully land you the job.
Can you get funding to re-do your GCSEs? Be careful with qualifications though, I was refused loads of jobs due to no paperwork, so I put myself through hell and racked up debt, and now I'm over-qualified...