If you go AWOL and are caught, you can be punished with detention and you might not get to leave the army afterwards.
The maximum penalty for AWOL in peace time is two years in detention (at Colchester).
If you go AWOL after you've been given an order to deploy in war, then it counts as desertion and the maximum penalty is life in prison, although such a harsh sentence would be unusual.
If you're thinking of going AWOL, go back to the list of questions and work through the page from top to bottom first.
If you're already AWOL, you can get advice by contacting At Ease.