Congratulations!
As someone who has already completed his university studies (I was in a university laboratory experimenting on geckoes when I first logged on to APS in 2004, with a gecko hooked up to that computer right at the time), I can give you some advice.
Studying Zoology is likely to be one of the most enjoyable and rewarding things you will ever do. It will also probably be the worst career move of your life. Most people I studied with enjoyed their course. I loved it, I completed my major in Zoology, I did my major in Zoology, and without sacrificing every other area of my life it wasn't going to lead to work which was all that great, and even if I did that it wouldn't have lead to any real money.
Studying conservation biology and ecology is probably going to be even worse as a career move, and unless you're a mindless hippy who wants to learn very little and just spend time in light lectures and university camping trips (which yes, themselves will probably be very fun and you'll see some cool places etc), the course itself is pretty lame.
Chemistry can be a good career move if you want to get right into it. Most biologists study chemistry. I did and I found it really interesting, but I didn't get a chemistry major and as far as primarily chemistry-related career paths go, my chemistry qualifications are worth very little.
I don't regret my studies at all, but like almost everyone I went to university with, I am not using my qualifications for anything. There are far more people getting these qualifications than there will ever be jobs for, and those jobs are not well paid. Many people I studied with ended up in menial work, the smarter ones started their own businesses, went into different fields, some became school teachers (and most of those eventually hated it so much they left it). I loved my years at university, and I wouldn't tell you not to do it, but be sure that you either have an alternative career path in mind and you just want to enjoy uni (from what I see, university isn't anywhere near as good as it was in the good old days anyway; there's a completely different feel to it now), or you are absolutely set on having a career in biology and you are willing to work your **** off to stomp over everyone else and get it, and still not get much money for it. If you do relentlessly pursue it, you will most likely really love what you do, unless you end up in some menial role in a government department or some other peripherally relevant position, which I'd find completely depressing.
You're at a massive crossroad in your life and you have many options to choose from. Choose wisely.
Best of luck!
