The EHRC Code is unworkable. There are no penalties for using the toilet you identify with (thankfully). If you are questioned about your gender, it is discrimination. Venue operators are not expected to become gender police. And, the vast majority of people don't care if trans people use the toilet they identify with.
I've been using the women's toilet for years and I'm not about to change. I expect most trans people will simply ignore the rule and go about their business as usual.