SICP is online for free (legally) from MIT's website, or there are some community version with cleaner layout. See: https://news.ycombinator.com/item?id=13918465

I've only worked through Chapter 1. The text is interesting, but most of my learning has come from the exercises. You should plan to do the exercises. Also, don't worry if you have to skip a few exercises and come back to them later. Don't allow yourself to be bogged down and loose interest over a single difficult exercise.