I struggled with Chem a lot at gcse but eventually it all clicked, and so far A-Level chem has been alright. (I am in my first year at the moment.) If you like the subject then take it, and if you feel like you can put the work to understand it it gcse and a-level. It does link well with your other choices too. However, it does get harder and you need the foundations of gcse to get AS and A2, especially organic in my opinion.
If you enjoy history and you like the topics you're doing in history a-level, because they may be very boring where you're going and thatll SUCK, then take it.
Do you know what you want to do post 18? Worst case scenario you swap from chem to history after a couple of weeks, that happens a lot of the time.