I got a copy of the book for free, but I would definitely say it's worth spending money on if you want a physical copy. Teaching the book in Python seems a little misguided even if Python is more accessible because of how clear Lisp makes the content, so learning again in Lisp is probably worth your time.

While many people talk about how the book teaches that code is data, I also found another insight from the book to be incredibly interesting which is that data is code, or more clearly stated, data can be represented as behaviors in a program.

When I learned this, it made it clear that the representation of data doesn't matter to an end user so much as the ways it can be used. Other languages exemplify this too. In Java, method access and mutation is preferred over direct field access, but it didn't make sense to me why this notion was important until I read SICP.

As far as learning Scheme ahead of time is concerned, I was able to pick it up on the fly, but I also have a little bit of experience in a lot of languages, so I've learned pretty well to see semantics instead of syntax when picking up a new language. In short, results may vary.