Gary, WWW has it about right. So do the others who say give it a go.
First step is to get the facts from the AFCO.
From your putative educational attainment it looks as if you want to be a direct entrant entering this year or next. This is not a negative mark as a direct entrant at your age is still developing and can reach a higher standard than a University graduate who is a WYSIWYG; basically their aptitude will not improve any further.
What will tip the balance further in your favour is performance at interview and performance in the exercises, mental reasoning, control, leadership etc. You exam results are not sparkling but they exceed the minimum. If your performance at OASC is satisfactory then you are in with a chance.