The RVC's Chemistry Champions course may be good. I only managed to do the Biology Champions course, but it was useful and gave some interesting insight into different careers within Biology and covered some content too, which allowed us to engage with the sessions more. I didn't manage to get a lot of work experience related to my course (partly due to lockdowns and covid restrictions etc), so included this in my personal statement.
I aslo took part in the Cambridge Chemistry Challenge at the end of year 12. That might be good, but I think your school/college will have to register.