I've left sixth form for college, but now I regret it!

I joined Sixth form at the start of September this year and was studying maths, physics and biology. After a few weeks I realised how much work I had to do and just wasn't coping with it... so I decided to go to college and study something a bit less demanding and now I regret it. Badly.

Once I realised that this was not what I wanted and that I wanted to go back to Sixth form, I got in touch with them and asked them if I could come back but they told me it was too late now. So now I was just wondering, is it possible for me to do one year at college and then go back to sixth form next year and start again?