Hopefully MG UK don't mind me sharing this - it wasn't marked as confidential.
So, it turns out my dealer was
NOT lying. Email reply from Guy P:
"There are a number of cars at the docks
undergoing software updates which is the normal process to ensure all new models have the very latest versions of the software required, that however has not been holding them up. We are expecting to start deliveries wk comm 16th September"
Unless
MG4Driver is also accusing MG UK of lying.
Guy P has also been able to confirm that my Cyberster "is actually on a ship and wont arrive until the end of the month, realistically that means the earliest we will get it to Inverness is in the first half of October." Very dissapointed