The other thing we did was encourage her to ask whenever we were out and reassure her we would always find her a toilet no matter what. And even if we had all just strapped into the car to head home and she asked we would get everyone out and dash through the shops to a toilet... and even if she did nothing once we got there we would praise her for asking lol. She usually asks once no matter where we are just to check out the new toilet but I'm okay with that, I think it reassures her to have a trial run to the toilet so she knows we can get there in time, kids can have a bit of anxiety surrounding making it in time when they are in an unfamiliar setting.