Windows – Disable Auto-Restart Prompt after Windows Update (in Windows Vista/7)

From Disable Windows Update restart nag:

To stop this service, open Command Prompt (Start>Run>cmd>Enter) and type the following command sc stop wuauserv. This will not prevent Automatic Updates from starting at the next boot. So don't worry, you'll keep getting Windows updates. Just don't forget to restart eventually.

From disable Automatic Update restart prompts using Windows Computer Policy
(was this the one you mentioned in your post?):

Start / Run / gpedit.msc / Local Computer Policy / Computer Configuration / Administrative Templates / Windows Components / Windows Update / and disable Re-prompt for restart with scheduled installations.

You can use a freeware product to Disable Windows Update Restart Alert Message With WindowsUpdateSilencer:

If you want to get rid of Windows Update notification then here is WindowsUpdateSilencer useful tool which runs in the background and will automatically silence all Windows update notifications.

(I have never used this program and can't vouch for it, especially on Server 2008.)

I'm on Windows 10 Pro, and your description sounds very similar to how I use my computer. The only solution I could find uses Group Policy Editor, which is not available on Home. However, following instructions from this article may let you install it.

Provided that works, following the instructions in this image will do the following: When windows is ready to install updates, it will ask you permission to continue as well as give you a list of updates it's trying to install. You can usually allow it to continue if it's just something like Windows Defender updates, but if you see something like "Windows 10 cumulative..." then if you let it install, it will promptly start trying to restart. So hold off on allowing those until you're ready to restart.