Hi Aspirant,
The best way to prepare for the GK and current affairs section (though this'll be a bit time taking) is to go through newspapers and magazines.
Since,you are already having some materials to prepare,you can easily shift to these if required after finishing your book.
The following recommended newspapers and magazines are-

*The Hindu
*The Economist.
*India Today
*Mint
*WSJ
*Frontline

Hope this helps.