Does this sound like an effective studying schedule for GCSE's?

I'm in year 10 and want straight A*'s in my GCSE's as I want to be a surgeon. I find that under a schedule I focus better and procrastinate less, so I have created one:
History, Bio, Chem require a lot of studying. Maths & Physics are my weakest subjects.

Mon Wed*
Biology 4.40 - 5.20
Chemistry 5.30 - 6.10
History * 6.20 - 7.00
(History: Saturday 2.20 - 3.00)

Tues
R.E, Spanish, Geography - 4.20 - how long it takes me (These subjects I find easiest and I finish studying them pretty quickly, they don't require much attention so only study one day a week)
Physics tutoring at 6.30 - 7.30.

Thurs
Physics 4.40 - 5.10
Saturday: 11.00 - 12.00

Thurs*
Maths 5.40 - 6.00
Saturday 1.00 - 2.00

Thurs
English 6.20 - 6.50

Friday - Day off
Sunday - Day off

During studying sessions I will do past papers, go over the specification and read my textbook, revision guides and exercise books.
I have included many breaks for free time. Is it too much? Too little? What should I add to it, or take out of it? Does it sound like a very good schedule to achieve my goal of becoming a surgeon? Thanks!