I was going to suggest the same that Annie. Since you are 18 (did you have a gap year?) if not you could try one year working as volunteer in some natural reserve or maybe a zoo or botanical garden. It looks the volunteer jobs are opened to enthusiast teenagers like you, so it would help you to decide if you want to do a university degree and in what sort of conservation project or maybe study as a technician to work in conservation projects.
As a child I dreamed to be in a natural reserve in Africa
. I ve just finished a phd in Ecology the past year and although I am very happy in university activities, I am not dealing with lions or forest conservation do you see?
Sometimes life takes you to other ways.
Anyway good luck!!