How does one start to study biology?
I willl be finished with my masters in physics this summer. And after reading the selfish gene a few months ago I developed an increasing interest in biology. Especially Zoology and all the connected evolutionary stuff to it.
I read some paper I found online, got myself copies of Darwin's books and read on various other sources. But I feel it's kinda pointless to just read here and there about stuff you may find online. Obviously books are good, but what I am looking for is a more structured way to go on about learning More about Evolution, behavioural biology, zoology etc.

Where would one start who seriously wants to invest more time into this. It can't be enrolling as a biology major though, because I intend to never go back into university once I'm finished. I want to do it in my free time.