The English Civil Wars (2010) by Blair Warden is a crisp book that will help you delineate your Levellers from your Roundheads.
The book describes the complex, multi-conflict times between 1640 and 1660. It’s got a lot more than a Wikipedia page but isn’t a 900 page epic that requires a huge commitment. Warden is a professor who has written many books about specific aspects of the wars and clearly knows his subject in detail. The book is a little confusing, but this is because the subject is confusing. The issues that drove the war are complex and the way that the disputing parties evolved means a clear narrative is going to be an over simplification.
Worth a read.