Yeah I read WL&C after a failed attempt at reading Capital (I had never read much Marx other than the manifesto at that point) and realized I needed to understand his economics first, as I felt completely out of my depth. Turns out reading Capital v1, the first few chapters are just like that! But I'm glad I read WL&C, like you said its short and gave me something to chew on for a year or so before diving back into the big book.

I edited my comment above about CotGP. All solid recommendations, for exactly the reasons you state.