I am assuming that due to the amount of time that has elapsed that this issue has now been resolved. However here goes anyway.
Are you waiting for your P60 to be presented to you when you log in? This is not how it works.
From the ArmyNET home page select pay (The Â£ icon on the top bar). You will then arrive at the page on which your current pay statement is displayed. Just above the pay statement is a P60. Click on that link and your current P60 will appear. There is also an option to print it out from this page.