When my UC was very very bad I had one of those cards, never managed to summon up the courage to actually use it when faced with a queue. With my ileostomy, I still have the right to one, but - know again, I would not use it.
Few years back, being driven to the Hastings by one of my daughters, we got caught on a long, very slow traffic jam. I desperately needed to empty my bag, and as we crawled through a village she pulled off into a pub car park, and I did go i n there explaining my need. They were lovely and I used their loos, then purchased some packets of crisps as I felt I was obliged to spend something there.,
Radar keys do help and most pubs have an accessible loo, motorway service stations are good, also.