try and get a job doing anything it doesnt matter as long as it brings money in,, if your 18 and still at home put your name on the housing register at your council and tell them its urgent (you can make something absurd up so that they look at your case before others, cruel but true.) when you get a house/flat you can also apply for rent rebate this means that you dont have to pay the full amount of rent, the government pays for most of it and you pay for a small amount. then youll be laughing when you have your own place. im 17 and have the same problem as you ive gotten a job (started on monday) and hope to be raking in the dosh soon and hopefull look for a place.
Good luck with it.
ps. what exactly is the problem with your parents, why do you want to cut them off completely?