Most UK stations have a pub which is run by SSP, e.g. The Mayfield at Manchester Piccadilly, Beer House at Manchester Victoria, Beer House at Glasgow Central. The toilets in these nearly always have a number combination lock fitted, however these locks are very rarely in use. You can just push the door. They're just there for effect. Saves paying 30p or more to use station loos.
If you're lucky enough to have a Wetherspoon in the station like at Leeds, even better, they are free, big and very clean!