Beer Machine

Is it safe enough to let the machine work beer while you're on holiday so that its ready when you come back??

yes

As a Mr. Beer? It should take 2 weeks to ferment. Do not be gone much more than that.

I do not know what a beer engine, but it seems that I need. a money machine.

Yes, as long as you keep a constant temperature. The beer will still be there when you return.