Unfortunately this is the price we pay (or don’t) when we save money by buying a less flexible ticket or combination of tickets.
Whilst it would ordinarily be ridiculous to expect you to wait almost 4 hours for the next train, it wouldn’t be GCs fault so they’re not obliged to help, and XC as an operator are unlikely to give a damn. I suspect they’d fob you off with some nonsense about splitting your ticket and try to claim they’re not responsible. They’d almost certainly reject any delay repay claim you made.
However as Haywain says speaking to a guard might give you some more options.
in today’s profit focussed anti passenger railway, the concept of passenger rights is largely out the window generally. It’s folly of people to expect the railway to follow ANY rules let alone offer assistance above and beyond (although the majority of staff on the ground are helpful and will do what they can).
I consider advances for smaller less frequent operators a risk which you have to be aware of when you purchase. I won’t purchase a Hull Trains advance to or from London and Retford because I know that if there’s a wasp on the rails near Brough they’ll cancel a diagram for the rest of the day and most passengers will be between 2 and 4 hours late, in part due to their limited stock and staff. Where as LNER will endeavour to stop another train at Retford or will organise ticket acceptance.