Hey as someone who had just done A level Chemistry (edexcel) I could say that it was actually one of my favourite subjects (I also did biology, maths and EPQ). If it's grades you are worried about then have no fear as resources on chemistry are readily available online (chemrevise was the site I used for all my notes) and full revision videos are at your disposal on YT (used Allery chemistry). As long as you have a good understanding and can make sense of the content taught you should be fine! Honestly A level Chemistry is a lot easier than GCSE as all the concepts are explained more clearly and you will see that as you go through the topics, that they all intertwine and make sense as a whole (they tend to explain concepts like bonding vaguely). Revision is straightforward and as long as you do enough past papers (including IAL edexcel ones too as they are good for practice), securing an A should be no problem. I like you, was predicted a top grade in GCSE and managed to finish A levels, with very little stress, with 3 marks off of an A*. If you clearly have a passion for chemistry I say go for it!