A Level Philosophy & Ethics or Psychology?

I am currently on my last year of studying GCSEs and am preparing to choose the options for my A Levels. My ambition is to become a veterinarian surgeon, so I have definitely settled on taking Chemistry, Biology and Physics. But I don't know whether to choose Psychology or Philosophy & Ethics. I am able to take 5, but I want to focus on my main subjects and not over work myself.
At the moment I average in A's in all my subjects, except English I believe, but much higher in the sciences(Triple Award) and will hopefully be able to get A*'s by the end. I did not take any humanities subjects at GCSE except full course RE(My school offers a short course for everyone who doesn't want to take it as an option). I believe I'm fairly good at written work, just that no one is able to read my writing and my English teacher seems to dislike me.
Please help!?

I'd chuck maths in there. Not essential but a good subject, like physics which you have chosen. I would recommend philosophy over psychology as it is listed as an A subject compared to psychology which is listed as B subject (http://www.trin.cam.ac.uk/index.php?pageid=604)