In Ankara, it can be difficult to find large collections of English books and novels. If you start to poke your head into the book stores you pass, you will eventually find one close to your house that has a small collection. In Kizilay, there is a bookstore called "Dost" that has decent collection of non-fiction and contemporary novels (pedestrian street, off of Ziyah Gokup, near the Metro entrance).
Also, D&R books in TunalI has an entire floor dedicated to English books but it is extremely expensive. Classics seem to be very reasonably priced here and Dost has a large collection. Another good option is Amazon.com. Amazon will ship to your house, and if you are willing to wait a few weeks, the shipping cost is not out of this world.