Adult Learner at College

Hi there, I've just enrolled at a local college to resit my Maths GCSE in order for me to progress on to my PGCE in a few years time. My university have changed the timetable at the last minute and on the evening I'm meant to attend I have to be in my teaching placement... So I will be doing an online course and taking my exam as a private candidate at a local independent school. So my question is has anyone withdrawn from an evening course? How should I go about doing this? In the ideal situation I could ring the college up and say I wish to leave... It was free to enrol on the Maths GCSE as I'm still in education and didn't achieve the correct result last time, would they ask for the fee's in return due to me leaving the course? Any help would be appreciated!

Thanks