:Well, speaking as a professional croc biologist who came from England with a degree in zoology, I can assure you it works! You won't find a course specialising in crocodilians, and to be honest you would be unwise to enrol in one. Having a broad outlook is extremely important, and while you can specialise in any area of biology you really need the bigger picture also.
:If you want to increase your chances of getting into the croc field, write to croc researchers whose fields interest you and ask their advice. See the world, and the work being done, for yourself. It will mean travel and time spent as a volunteer, but it will provide a groundwork you won't get in the UK.