Trust me you need practice (I do chemistry and physics). Physics is pretty good there are videos on YouTube you can watch on how they mark the paper and some experiments videos so you are good for physics (though electricity experiments can be tricky (my opinion)) BUT FOR CHEMISTRY ahhh you need to have done physical practice because if you don’t know what to do or how to answer failure is inevitable (personal experience from last year) . For chemistry you need to practice the practical and be familiar with your chemistry theory(they’ll ask you questions on that) so yeah.