Heey, I'm currently in my second year doing sociology!
1. What topics-
Education, Crime and Deviance, Theory and Methods are compulsory. The other two topics are optional - although most schools choose Families and Households and Beliefs in Society
2. Difficulty-
Personally, the concepts within sociology can sometimes be easy to understand. It's just the amount of content you have to learn. There's a LOT. If you want the top grades, you need to know as many studies and researchers as possible. So I'd say it's difficult in the sense that there is a lot you need to know but actually UNDERSTANDING what youre being taught isn't too bad.
3. Manageable -
Yep, I'd say it's manageable, but of course it's different for everyone.
4. I'd recommend it, I am doing it at uni so yeeepp!
There are many links between english lit and sociology as I do both - in english you need to know certain critical theories, and you learn about those in sociology so yeah it will slightly help out
Hope I helped!