Just found this on the Money Saving Expert site. It lists all the council MOT test stations which the local authorities use to annually MOT all their vehicles - buses, ambulances etc. So? Well council MOT stations have to also be open the public. However, they're not repair centres, so unlike your average garage they're not interested in failing a car on something false or trivial purely to make money out of a massive repair bill.
Has anybody used the council test centres before? Seems like a plan...