I've been an OU student for some time now. Although I began with them, I took a break and did a full time Arts degree before coming back to them for the hell of it.
Like you, I left school with very little other than bad memories, and OU study has given me the confidence to branch out and study elsewhere, in turn furthering that confidence.
OU are very good with 'first time' and under-confident students, starting you out with the basics and building up from there, although you'll get the most benefit if you're totally honest with yourself about your existing abilities. If necessary, start with a course that takes you back over stuff you've already done.
True, you don't get the grants and loans with OU, although they do have a fund you can apply to if things are difficult. You can also pay your fees by instalment and defer indefinitely if you need to.
You are not living in a dream world - all you have to do is believe in yourself and not be too proud to seek help if you're struggling.
Oh, and summer school's are mucho fun!!!!