I've done everything in Chemistry as I have done for Physics, we did a unified Physics exam today and I was about 2 marks off an A*, my teacher made it so it was harder than the actual one as well so I'm fairly confident I could get an A maybe even scrape an A*. But I've done everything in Chemistry as I have done for Physics, and still struggle loads, we haven't even started doing unified for chemistry lessons though but thinking about it terrifies me. I can barely even scrape 50% on a chemistry exam and the grade boundaries are insanely high for it (it's around 80% for an A).
What I have done is just go through the book, answer questions, I've gone through Organic about 5 times now with 2 different books and can't get more than a B on any old spec past papers.