In my opinion, one of the best things you can do is to learn ahead, especially for chem. This year I self-taught myself the chem course before we reached it in class, and it was incredibly helpful. Even though the first time learning a new topic was difficult, by going through it in class again and knowing where you need help with so you can ask is very valuable. This also gets you ahead in SACs as well, which is also really important.
I would suggest start learning unit 3, or if you don't feel like it, at least skim through the contents so it's more familiar when you reach it in class next year. If your school gives you edrolo, utilise that, I know it may not be for everyone but I taught myself through edrolo and it was really helpful.
Another free resource is Chemisodes, a podcast series that goes over the course. However that was the old study design, so be aware of the changes/additions.
You're a straight A student, so your work ethics must be really amazing

Chemistry won't let you down, if you're willing to work hard for it
Oh and AN will always be here to help you next year
If you would like, you can PM me and I'll send you some chem stuff
Have faith!!! And enjoy chemistry, it's an amazing subject