The best thing you can do is go down to your local careers office and ask them for advice. I don't think you can get through the UCAS process wit the qualifications you have mentioned. Try
http://www.ucas.com/ for some advice, and
http://www.connexions.gov.uk/ should be able to help you with some of your questions too. (I know it says 16-19 but they should be able to give you some leaflets at the very least and/or explain to you how the system works.)
I'd also try contacting your local Further Education college because they will be able to offer you advice about courses that lead to University. It's possible a one-year course will get you qualifications enough to go. As for financial help as long as you are under 25 I think you can get the student grants. Again the links I've provided should be able to help you with this or contact your local LEA (Local Education Authority) as they are who priovides the funding!
Good luck! I should be heading off myself in 2 years and I'll be 20 yet so you won't be that old compared to all of us!