I don't do chem, but I do bio and believe me it is solid. I got an A at GCSE and I really enjoyed it, but there is so much necessary content to learn and understand at A level it is definitely a difficult subject to take. I actually regret choosing Biology over Maths, the papers for bio are something like 10% maths, 20% content you've learned and then 70% application where you have to basically understand your content and apply that to unknown situations with weird molecules you've never even heard of before. It's very difficult but rewarding when you get the answer I guess