I read your question carefully Busukxuan an then I read the responses an besides Max Williams an you pointing out The Hobbit reference, I was really surprised that no one mentioned the book.
Like I said before Busukxuan, I read your question very carefully an I understand that your looking for a literature meaning to the phrase. Before I continue my opinion, let's first make this clear.....yes the meaning to the this phase is based in the environment of adventure or misadventure or both but travel does play a big role in the meaning (I'm not really sure about using it in idioms but then again I been slacking on my literature so I wouldn't know at the moment).
Now, with that being said; no one mentioned the book. If one was familiar with The Hobbit an The Lord Of The Rings, they would know that the main protagonists Bilbo Baggins, Froto Baggins an lastly Samwise Gamgee are the authors to a major story saga that they experienced first-hand which would later be titled...you guessed it...There And Back Again: A Hobbits Tale/Holiday.
However, Bilbo Baggins is the main author of this extremely enormous book due to the fact that he began creating the book in his perspective. Then from there, the rest is history. Though what the title meant to him is pretty much what everyone has been saying. The sense of adventuring. Busukxuan, your ideal of the meaning towards the phase is correct but like I said though im not sure if the phrase can be used as an idiom.
If I remember correctly...the definition of Idiom is a group of words/expression or phrase whose meaning is not exactly accurate or predictable to the words/expression or phrase given.
While the phrase "There and back again" is pretty straight forward an does not have another subliminal meaning [at least not to the person (hobbit) who created the phrase]. Bilbo Baggins decided to go on many peril adventures (THERE) an when those adventures reached their conclusions he would go back home to The Shire (AND BACK AGAIN) and document his knowledge that he learned so that he can share his knowledge to his fellow hobbit friends an family.
This is the true meaning to the phrase "There and back again", one who went on an adventure from home only to return home to speak and share their learned wisdom an give birth to knowledge (storytelling). I know this wasn't the answer you were most likely hoping for.
It wasn't an idiom-related answer but you did ask for the meaning. There was aloooot more things I could've added but I think this waaaay more than enough. I hope this was helpful.