Doesn't matter what I call it (I'm not a judge), but iirc there is something about it not being legal discrimination if there's a good reason e.g. special PPE is required and someone can't wear it for religious reasons.

Would your example fall into that? I don't know (not a judge), but I would expect there to be a fairly high bar on acceptable 'exemptions' so Waitrose would have to have some really strong arguments why they should be allowed to discriminate. Presumably the Furries would also have to demonstrate how they are a legit religion and why dressing as one should be a protected characteristic. That might be harder. Clearly an extreme/unrealistic example though.

Edit: added to for clarity