I've been worrying about that too...pretty much everyone has a degree. Don't talk about graduation! I really admire you wanting to work for Childline, that's a pretty hardcore way of bringing good to the world. I couldn't do it. I work at Oxfam Books, which is an easier way to feel less bad about my part in our ****ty world, even if what I do is pretty indirect..
what does 'supporting statement' mean? Just reasons why you want to do it? I guess refer to any previous experience you might have done with a voluntary organisation, something to show you're dedicated, compassionate and probably able to think quickly. I can't really help, I'm terrible at that sort of thing. Good luck.