From what I am reading and hearing, I think 4th July could be mayhem and I am glad that I don' t have anything in the diary. I'll be avoiding pubs even more than normal on that day. Some of the local pubs are talking about not opening until 6th.
There is a lot of use of 'should' in the guidelines : pubs 'should' obtain details of customers in case they need to be traced and tested, etc. To me, should means must: it's the same as shall. But to many people (including some international standards committees who go out of their way to redefine the word) it means, 'well maybe this would be a nice idea but don't stress if it doesn't happen'.