Hi Rabia Welcome to the world of CSS. Its good you have decided to opt for psychology as one of your electives.
Yea you can prepare psychology on your own but can not cover whole of the syllabi on your own. There are topics on which you need to have guidance from a psychologist. For that purpose, you can contact any one of the faculty members from the psychology departments of GCU and PU.
By the way, you can also contact me in this regard.
Regards.