You have clearly understood UPSC requirements and Graduation through correspondence does not impact your chance.
You should prepare for coming Civil Services Examination 2015 and concentrate on immediate requirements.
You are little late to start as you need at least one year time to prepare effectively. Now, as you start only a few months before Preliminary Examination you will find it tough; but, still you have enough time to prepare and with hard-work in right direction, you can do it.
Commence preparation with General Studies (Main Examination oriented) and select your optional subject without delay. Prepare a strategy for study-plan and adhere to it strictly.
Start with NCERT books for building basics and cultivate reading newspapers daily.