I am scared I am going to fail Maths tomorrow?

Me and my class are really smart but our teacher is sh*t he makes mistakes and we copy it and write the wrong answers! Its a real GCSE 30% f******* and I'm scared I am going to fail :( I'm just trying to cram everything in an revise and pray I do good. But what else should I do?! The test is on Algebra, Graphs and calculating Volume with changing factors. Its pretty hard stuff. AND MY PARENTS ARE GOING TO BE ANGRY AT ME! WHEN ITS MY SH*T TEACHER! - in my class the smartest kid in school does not understand my teacher at all.... Help!