Actually, it is unnecessary to study AL Psychology or any other subjects before you have entered either local university or those in foreign countries.
But if you want to become a psychologist (actually there are many types of psyhcologists), you ought to study psychology in university. Most commonly, you need to study at least to a master degree in a particular field of psychology.
There are several kinds of psychologists, for instance, clinical psychologist, educational psychologist, neurological psychologist, etc.
I am not sure what to study in university, but i know the syllabus being studied in year 1 is very similar to that in AL Psychology.
As I am studying AL Psychology now, i can tell you the syllabus includes nature of psychology, learning, memory, developmental psychology, psychology of personality, perception and attention, psychopathology, social psychology, individual differences, biological psychology, motivation and emotion, consciousness and scientific methods in psychology
but i think the content will be more complicated in university and more specific in higher years, i.e. specific for a particular area of psychology.
In conclusion, entering university, no matter local or in foreign countries, is rudimentary to become a psychologist in the future. After that, you should study psychology and at least get a master degree in psychology.