Any idea that you will get a new baths out of this is pure fantasy. First there is no room on the Buxton lane site for a wet and dry facility + off road parking. What will happen is the baths will continue for a few years after the supermarket has been built and then to save money, because of the falling numbers, close, long after the developer has left the area.
The record of supermarkets building new swimming pools is not good, the last ones Tesco built just included the outer shell, leaving the building empty as the council had no money to provide all the internal bits (boiler, filtration etc.)