Player turn vs Game turn & deciding game end.

Ok, so it states that at the end of a game turn if a player has no models on the board they automatically lose.
I understand the concept behind null deployment, but does the same apply for any game turn.
Let's say I'm going 2nd, on turn two my opponent had his "players turn" and destroys all my units, am I able to still have my "player turn" and attempt to bring on reserves?
If I bring on reserves before the end of the "game turn" then the game continues, if I fail to bring on reserves the game ends.
Is this correct?

Yes, in short.

THe game turn is comprised of two parts, player 1's turn, and player 2's turn. The game turn only ends when player 2 has finished their turn, so if you are going second and your opponent clears all your units from the table in his turn 2, you still get to roll for reserves and only if you fail to bring anything on does the game end.

Turn summary is on pg. 17.

Otherwise know as getting "tabled".