Not really, to be honest -- most of what I learned so far about Golang was from their website's documentation and examples. It is not hard to learn in my opinion, especially if you also know some C (since you come from a PHP background, I assume you could manage Golang with a few tutorials). You should probably take a look at Go by Example to see for yourself.
As for "schools", I won't recommend any simply because the only online courses I was recommended were paid ones, and they also did not seem to be extremely good. Furthermore, they were in Portuguese, which is my mother language.
PS. I was also surprised at how Golang does some trivial stuff like connecting to databases. Did you know every database "connection" in fact works as/can work as a connection pool? You end up writing code as if you're sharing a single connection between threads, but in fact, you're not.
I see that you're using Acme over there... :)
Are you somewhat inspired by how Plan 9 handles e-mail? I was wondering if I could do the same but for 9front.