@ all users,
no need to confuse yourself so much . those who opt political science go through part 2 first then come towards a constitutional law .
you need to go through past paper in order to get idea about questions asked in exams. secondly you need to study comparatively by comparing one country law making process to other country, concept of sovereign, parliament etc as well as implementation of theories like rule of law , separation of power etc .
some senior here available for your queries and i can also try to help you as much as i can.