It's a funny thing, this growing older phenomenon, which I am still not used to as I feel just the same as I ever did, apart from the fact that (and it is a fact) if I take my dogs for a walk and don't 'go' beforehand, I always always have to 'go' behind a tree, half way round; or have to face the reality that when I get home I will pee myself running to the loo.... after I have got out of the car and unloaded the dogs... unlocked the front door... all whilst desperately doing the pelvic floor to hold the Niagra falls in and failing miserably 
The rule is to go before you leave the house.
Shops with a restaurant in always have public loos, and shopping malls have them too..
Not sure about other parts of the country, but here in Leeds we have plenty of public toilets.