How badly will coursework effect my AQA A Level PE Grade

I've been given very little indication about what I need to do in my coursework and after many months of working on it my teacher has decided that what we're doing isn't correct after previously telling us otherwise.As you can see by the lack of direction given, I'm very worried about my overall grade. If i fail my coursework, does anyone have a way of working out what grade i need in the exam for a B. Its split 30% coursework, 70% theory/exam.For example, I've recently achieved A* in my mock exam, but at this rate feel its unlikely I'll get above a C in my coursework.Thanks in advance!