Resitting Chemistry A2 in Jan - Not possible?

Hi all. I would like to improve my chemistry grade from a D to a B, but in order to do that I'll need to retake all my A2 modules. This would be fine except that I'm unsure now whether Edexcel do resits during January for Unit 4/5 and 6 - including the practical. How would I be able to go about doing this, if it is possible at all?

The reason I'm keen on doing it in January is because I'm currently outside of education and I don't really want to be doing some exams in January then in June again, I'd rather get it all over and done with once. Not to mention that I have other plans for January onwards which perhaps interfer with them. (abroad.)

If anyone could give me some advice. It'd be really appreciated.