This is pretty simple.
There is one world. You can play as you wish. You can verify if you wish. You can subscribe if you wish.
Or wait until this game is stable enough to support a permanent world. Though to be honest, sporadic resets are healthy at this point.
That's it. Boomp. Done.
There is no singleplayer client and i doubt they'll magically pull one out of their busy asses to sell to one dude.
It's remarkably easy to get to taming/cheesing/steeling. It just takes time (or if you join late world, looting dead villages is pretty fun).
It doesn't seem like the game for you if you just randomly quit for a long time. All your shit will die and decay even in magic singleplayer/lan land.
This game is basically a second job, and your boss gets pissed if you miss a day.