I wanna leave

I wanna run away but I'm too young, don't have much money, I'm not smart and don't know were to go My older sister is physically and mentally abu sive and my family barley try to stop her and if she does it again I'm gone I'm in England so it's kinda hard to find somewhere as a teen I don't know what to do but any tips? I know if I don't leave I'm slowly k!//!ng my self allowing her to do this for the rest of my life.