Hi,
I currently take 4 A-levels (different combination, but mostly stem subjects), and am in Year 13 now.
4 A-Levels is not impossible, as long as you are sensible with your time. It was probably a mistake for me to an EPQ on top of the 4 A-levels, since that was rather overwhelming.
In my school, everyone who took physics as part of 4 A Levels dropped a subject after the first year. With that said, it's definitely possible if you are very committed.
Another option is if at the end of the first year, it becomes overwhelming, you can usually drop one subject and take it as an AS instead. That way you still get a qualification for the year's work.
Hope this helps!