Thank you for the kind words folks. I'm feeling better about it after a bit of reflection.
It's odd, but it never felt 'right'. I suppose I should have known when the FD turned up 35 minutes late for my first interview and didn't have the decency to apologise to the fat bloke sat sweating in his bestest interview suit.
I was tempted to ring ACAS, but I don't think I'll bother. What would I gain other than a load of stress?
Br. They've promised payment of my months notice period. I have also requested payment for accrued holidays (5 days) but am not holding my breath.