They'd be better off applying for a change of use for the old new look space , and turning it into a bar or restaurant.
The gym is a bit more complicated, I don't think it'd work as a retail unit tbh, unless some sort of staircase was created within new look and they turned it into a double floor retail unit.
I had noticed planned had been out forward to turn the space above millets into a dance studio though, dunno what the status of acceptance is, but there was notices put about town, so maybe something like that ?
A gym could work there, if they used all the space I think.