Speaking as someone with an assistance dog trained by an ADUK charity (and yes, assistance dogs come in all breeds!), this makes me uncomfortable.
UK law on assistance dogs is quite broad under the Equality Act 2010. A dog does not need to be trained by an ADUK charity to qualify - even though I personally think that should be the standard. There is also no legal requirement to wear a uniform, carry an ID book, or register on any official database.
You do not need to prove your disability at the door. However, if a business refuses entry, taking action against them usually means taking them to court to prove you are disabled, that your dog is an assistance dog, and that the refusal was unlawful. This lack of a clear, formal system is why these issues happen.
It leaves disabled people who rely on assistance dogs in a difficult position when we face illegal access refusals. Taking legal action is stressful and expensive, and unlike large organisations, like say, Asda who regularly refuse me access, the individual assistance dog owners rarely have access to legal support. I certainly don't have any BAME or similar charities helping to pay for it (so that part did annoy me about this case!)
It feels unfair that we effectively have to fight to prove our disability just to exercise our basic access rights, much like the dehumanising process for claiming disability benefits or requesting adjustments at work.
So whilst she does sound batshit, I'll reserve judgement on the access matter for now.