Get a revision guide for your specification as a first step. Obviously, not every detail will be included in a revision guide but a simpler understanding of something first might allow you to grasp the full concept. The thing with chemistry is it takes a while to get but it will hopefully click at some point once you have a foundation of knowledge to apply.
A2 chemistry doesn't get any easier but if you try and understand it and then look at past paper q's on the topic it will help you identify where you're still weak. YouTube has a lot of good videos even if they're not spec specific, as does Snap Revise (costs but it is spec specific), and of course ask teachers or a different teacher to yours to have it explained a different way.
Speaking to medics and other hopefuls, I've found "chemistry is hard" to be the general consensus. Even if it's enjoyable, it's hard, and a "necessary evil" for medicine.
It's a good idea to get some work experience shadowing a doctor, and then some voluntary work as well, but also shadowing a nurse or a midwife to see which healthcare career you'd like to follow, then you can make a better decision about whether to drop chem or not.
But, if you learn the stuff and then practice applying it - which is the most important thing with chem imo, you should be fine going through the year if you keep on top of the workload.