Ahh.... Solution found
Press Windows-R. Type “servicres.msc” in the box and press Enter. Scroll down the list that appears to the item “Automatic Updates”. Right-click that item and choose “Stop”. All done. No more notice.
When you do eventually reboot (at your lesiure), the service will restart so that you’ll be informed of future updates. But you won’t be annoyed for the rest of the session.
OR
Press Windows-R, type “net stop wuauserv” in the box and press Enter. Done! A cool side effect is that next time you want to do this, the command will be in the autocomplete dropdown of the Run box!
Both methods give the same output