YESYESYES. Don't make my mistake.... I went to the same Sixthform (leading up from my high school) but I hated it to begin with, and everyone was like "don't worry it'll get better" etc. But it didn't o.o I'm now in A2 and regret not moving so much...
My advice to you, is depending on how well you think you can manage to handle the stress of catching up with new modules and exam boards, then move without a second thought (figure of speech) but on a serious note, do a lot of research into the sixthform, like their percentage of students who get top grades in bio for instance, or percentage of students who get into oxbrige or medicine or whatever.
Feel free to PM me and good luck