I'm following up to describe how I was successful in getting Copilot removed from my Office applications.
(I'm running Windows 10, based in Australia, and had a Microsoft 365 Family license expiring in early December).
The answer is "classic". Microsoft 365 Family Classic or Microsoft 365 Personal Classic (subscription) or Office Home 2024 (one-time purchase) do not contain the 'connected experiences', and do not contain Copilot.
However, you can't get Family/Personal Classic without direct support from Microsoft customer support.
I followed others' instructions to log into my Microsoft Account, find Microsoft 365 in my subscriptions, click 'manage', then 'cancel' in the hopes of seeing the fabled "Switch to a subscription that’s better for you" option in order to select Classic. But when I hit 'cancel' it tells me:
"We can’t cancel your subscription. You have already paid for your Microsoft 365 Family subscription. It will expire automatically on (DATE)." (the brick wall)
So I searched Microsoft 365 plans, which took me to a microsoft.com page. I clicked on "Questions? Talk to an expert" in the bottom right corner to start a chat. I opened with "Microsoft have recently embedded Copilot into Office 365. I will not be renewing my 365 plan because of this. I understand however we can sign up for Microsoft 365 Classic, which does not have Copilot in it. Can you please give me more information?"
I believe the staff have been coached to offer Classic plans when met with "I will not renew my subscription". The very helpful support/salesperson (no, I'm not being sarcastic - he actually was incredibly helpful!) walked me through the steps I described above until I hit the brick wall.
But he then directly assisted by cancelling my current subscription, and signing me up for a 'Classic' plan. It did mean I had to forfeit the balance of my existing subscription (which in my case was only 10 days), but I now have Classic. No connected experiences. And no Copilot.
After signing out of my Office applications, doing updates and a couple of restarts, and logging back in - I'm now Copilot-free.