I've never heard the evening meal being called 'high tea', just 'tea' or 'teatime'. I'm originally from the North West of England. I'd always thought 'high tea' was a mid afternoon snack of tea and cakes, as depicted in Victorian and Edwardian books about upper class English life, which of course bears no resemblance at all to modern day life in Britain.
In the North West it's usual for people to say breakfast, dinner, and tea. With supper being interchangeable with tea. It can sometimes mean a late night snack too.
On moving South you generally hear breakfast, lunch, and dinner for the evening meal.
'Pardon' is another odd word. 'Pardon', is a normal response in the North West if you don't hear someone and would like them to repeat what they said, but in the South of England, some people see nothing wrong in simply saying 'What', which sounds rude to me. This probably has its roots in the old fashioned class system.
On the subject of greetings, I've always thought the formal 'How do you do?' with the automatic response of 'How do you do?' without the expectation of a response to be rather silly.
In the North West you hear 'Are you all right.' or simply 'All right' all the time, along with 'Hiya', both delivered in what to my ear is a rather annoying high pitched sing song voice.
For birthdays, as already stated, people tend to say 4th of July, 10th of November, etc.
The trouble is, due to fashion, and the influence of modern global media, the language is constantly in flux, and what might be accurate today in one social group, may not be accurate a few years later.
A perfect example is the modern use of 'like' and 'love'. Just about everyone under 30 seems to say 'I am loving it' or 'I am liking it'. If you point out the verb tense is wrong, you will then probably have to explain what a verb is, and by the time you realise you will then have to explain the differences between dynamic and stative verbs both parties will probably have lost the will to live.
