Its not easy when you are on your own, without the encouragement of the workshop leaders. But can you take heart that you are showing a change of attitude: before, you would have been glad the toilets were empty, or may have avoiding going in. Now you are annoyed that they are empty - that has to be good. One things guys say is that the toilets often are empty, which shows how often they were worrying unnecessarily. You can actually visualise other people being in there; saying to yourself there is a guy two urinals away, or imagining there are footsteps approaching.
Can you get to a motorway services, or a shopping mall like Brent Cross? It may be further to go, but say once a week it would be worth it.