Hello
You can choose a course which will help you with PCS exam.
You can opt for BA in History, Geography or Political Science, because these are also part of the PCS syllabus, so they will help you with the preparation.
Also the class schedule is relatively relaxed for BA courses, so you will get a lot of time to prepare for PCS exam.
You can check top colleges for these courses in UP itself. The admissions will based on class XII percetage.
Start your preparation with NCERTs of class 6 to 10 social science subjects. Late on you can move to standard books such as Laxmikant, Spectrum etc.

Good luck