Hi there,
I don't study geography, but I do study chemistry for A-level. I've always struggled with chemistry, but managed to do quite well in it at GCSE (8). Chemistry at A-level is different to GCSE, but I'm pretty sure all A-levels are. I would say that it is difficult if you don't get it (or if you can't remember things!), but overall I would say that it's worth it! I really do enjoy it, especially the PAGs (practical assessments??) but overall, it is, at the end of the day your choice what you take. If you enjoy the subject, are doing decent in it and it will/may help you get the career you want, then go for it! Same applies to geography.