I did all of these at AS, and I dropped Physics at A2 (not because of the workload, I just didn't like the subject enough!) It was completely fine for me, I didn't really have to do too much work and it wasn't very stressful either. Definitely way less work than coursework heavy subjects or essay subjects! As long as you are reasonably academic, are good at math and enjoy sciences, you'll do fine.
Also, I really think that this helped me out with uni applications - despite what everyone says about unis only wanting 3 A-levels, my offer is for four, and so is everyone else's that has an offer for my particular course.