SuperSearch is a great place to start for journal articles, books and almost everything else the library has, in one easy to use interface.
For searching with more focus and precision, try one of the databases recommended on this guide.
These databases contain sociology-specific materials and can be accessed from this guide or directly from the Databases List on the LTS website.
When you find an article or book that is useful for your research, you probably know to consult its bibliography or reference list to find other potentially relevant sources. In this way, you're tracing the scholarly conversation backwards in time. But you can also trace citations forward to find newer scholarship that cites the source you have in hand.
You can also search within the results to find only sources that mention a particular work or other keyword.
You can also try Google Scholar's "Related articles" link, which uses Google's proprietary algorithms to pull up similar articles.