MP, your BOE can't force you not to get a car and not to get the insurance you want. They can only tell you not to drive it when you are on the clock.
30,000 is a lot cheaper than 80,000. The coverage might not be as good, but you will need to look at your own driving environment and style to decide what you want. I still think you can get almost the same coverage you would get with a private company at 8man for less at city hall. Also, insurance on a Mira will be less than a white plate (the quotes I was giving you).
I can understand not wanting to mix things up at the home BOE though. Sounds like you are in a tight spot...