The absolute worst ever food from a military mess was the Army camp I stayed on for my intelligence course for Pre-NI training on the southeast coast... The name eludes me right now probably due to the trauma, Ashford?...
Could it be St Martin's Plain at Folkestone? Spent two days there, tried to eat the unidentified substance that was offered on arrival, then went to the nearby Tesco to get something edible for the rest of my stay.