The suggestions to walk 20 miles around unlit roads and/or along a beach between 1 and 5am when the temperature was below zero really should win some sort of RailUK award for sheer insanity.
The best suggestion for the OP, in retrospect, was to screw the rules, just get on the train getting you closest to your destination, alight at a staffed station, attempt to raise help from the railway and failing that take a taxi and claim it back.
Taking the railway’s advice here led to the OP unacceptably surfing night buses all night like a homeless man. I’m surprised he isn’t angrier about it. I’m a big fan of just going ahead and doing whatever in these scenarios, aware that getting forgiveness is easier than permission. Not everyone feels the same way though or has the same self-confidence, I recognise.