my low A level grades in science are the result of mitigating circumstances?
No. The CFG0 course is designed for those who have not previously studied science subjects at A level. If you have already studied the subjects required for medicine at an appropriate level then this course would involve too much overlap with your previous studies. You could consider re-sitting the A levels to gain higher grades. This option would enable you to apply for four medicine courses and also give you more time in which to gain more relevant work and voluntary experience. You may also consider taking a different related degree course then applying for medicine again as a graduate.