I come in and find my PC has rebooted after an automatic update and I have insert my password again to get things going. I dislike this intensely and would like to do the updates manually at a time of my choosing. I have looked in the Win10 forum but cannot find anything relevant (probably a man look).
I have been caught out with an automated reboot too (when I had work left open! It was saved thankfully).
You could try to disable updates, but if there's a critical security hole found then you may miss out until remembering to update. Perhaps disabling the automated reboot would be a good compromise (just my thoughts anyway)?