How do i find some where to live if i'm not from this country?

i moved here to join my dad and his wife but now my stepmother has kicked me out because she doesn't want to be reminded of my mother, i'm 18 and a full time sixth form student. how do i find a way to stay in this country and finish school? i'm not british and i need a way to stay here but i cannot live with my dad and his wife.