Should I follow my head or my heart on university course?

You would be happy to know in university, you will be able to follow all of your loves. In University, you have a choice of choosing a major, or a major and a minor, or a dual major (two majors) or a dual major and a minor. Note on the last 2, you may need to get approval from your school.Your A-levels tell where your heart lies and at University, you can do that. Also, it will depend on the school you choose as all schools don't offer all of the above programs. You are right that your loves won't have you making millions but what if they just have you comfortable where you pay you can pay your flat rent and bills? Wouldn't that be ok too? Also, it'll be ok to change your mind once you get to university. Ask many former University students (even ur parents, teachers) and they'll tell you it's ok. Here's my question, how will you paying for school? If it's your own money or a combo of loan/grant/work then plan wisely. Unless you receive a particular area of study scholarship, you'll be able to choose any major you wish. Have you chosen a school yet? If so, call the school and ask to meet someone in each of the majors you are thinking of. As any university student can tell you and you will find out once you get there, is that there's more to a school then what is in the brochure. You can find out about certain professors and cles. As you have 18 months before you attend University, utilize the time calling around zoos and aquarium and see if you can meet with those in the fields you are interested. Math is such a wonderful tool which you can use with your Zoology and Marine Biology that you may not want to forget about it totally. Here in the states, some Colleges and Universities offer programs where secondary students can take university courses before they graduate from high school. You should ask your school counselor/adviser if any programs like that are offered where you are. If it is allowed, you can start taking some courses in the fields you're interested in to see if it is really what you want to go into. Also, if you let a University know, they can arrange for you to observe a cl in action to give you a peek at what University is all about. I think I beat you on the long-winded part ;-) but hope I gave you enough info and tools to help you in your decision. I found some links(tried not to put in wikipedia) that I posted below to help you as well. I wish you the best of luck and continued success in school! Also, don't forget to have a social life between all of your studies and work. Humans matter too. ^_^