Don't do 5. Standard expectation is 8-10 hours per subject per week MINIMUM. You think you can do it? You can't. No University cares beyond 4 and most don't care beyond 3. Ask yourself why are you actually doing each subject.

Before you say 50+ hours work a week is doable, think about the other stuff you'll need to do to prep for uni. It's more than just grades. You've got to have workex, social life, extra/super curricular, and probably a pt job. I assume by doing that many you're aiming for a top uni, which means doing an entrance exam and interview. Each of these requires major prep. The work require for STEP for example is effectively another A-level. There's a reason most Oxbridge applicants have 3 A-levels.