...apologies if I have misunderstood but if AppleCare is for 24 months, I have only had my 8 Plus for 12 months.
When I hand back my 8 Plus, in order to upgrade, what happens to the remaining 12 months of AppleCare - does it then just cancel?
That’s right. Apple care is tied to a device and not transferable. When you upgrade, say after 11 payments, you’ve only paid for 11/20 of Apple care (the months you’ve had your 8+). The new upgrade on IUP is a completely new agreement, credit check, initial £69 all again.
I’m sure there will be people who have IUP but may not pass the credit check second time around when upgrading