Does it rely on iCloud for that? And is the E2E only enabled for Notes if it's enabled in iCloud?
If so then the UK does not have E2E Notes.
It does not, although you can open notes in iCloud via a browser, and I’m not acquainted with how that functions in the UK (and if it’s available), mostly because I don’t do it.
It most definitely does. If you're using your gmail account as your AppleID. You can find all your notes unencrypted under a Gmail label called Notes
You didn’t choose to E2E encrypt them. You can find your unencrypted notes there.