It may be worth a call to the site and ask them how they accommodate to stay within the law. I know in the US there are some exclusions to the accessibility laws but most venues have found a way to accommodate all.
I’ve never tried alternatives like “go girl” urination device. Maybe an alternative if there is a private place? My husband has UC so was very nervous about starting the building process on property we had bought before we could even have a “porta potty” delivered but found a device they sell for camping for people to take backwoods. Basically just a fancy bucket with a lid like a toilet where you could just haul it out. It worked for the initial weeks until we got to the point that we had a driveway in and a porta potty could be delivered for use…not the best option but it served it’s purpose! There is always a way!