That is really bad, Superbunny.
Let me tell you about my experience. I worked in industry for 9 years, then did a PGCE. I taught for four terms, and then went on maternity leave with no intention of returning. I had a three more children, and spent four years in the US in the meantime.
After a work gap of 8 years, I decided to return to teaching. I had a couple of interviews (they interviewed me, lol, with very little evidence on my CV), but the feedback I got was that I needed more experience and they suggested supply. I found a local(ish) agency and they did the CRB paperwork for me, but only found me a few days of supply work. In my local paper there was an ad for the nearby international school to do 'sub work' - they snatched me up. I did several weeks with them before being asked to work at my DS's prep school for an absent science teacher. That lasted two terms and was fab. It gave me the necessary reference. I did a couple of other long term covers (maternity stuff - importantly, it meant I was doing the full job with planning and assessment as well as teaching), and daily supply at one school.
I did supply/contract for two years before landing a permanent job - which is fab. I love it, and will stay here until I retire.
I did not think much of supply before I tried it, but it was great. I had quite a few rotten days, but at least learnt something from them. I could experiment with my teaching style (eg should I be ultra nurturing, or shouty, or results based?). If it didn't work, I could walk away and vow never to do that again.
Do persevere with supply. Send your CV with compelling covering letter to the Headteacher of local schools. Someone will put you on their books, and once they see what you have to offer, you will become their first choice.