Apart from thinking about this......
There are a few other "constants" to bear in mind.
Weather - Last year we were there in August, so there was a chance of good weather. (Don't think we got much though.) This year's visit is in June, so I will not pack more than one pair of cropped trousers, and I will remember to take shoes with toes, and a few pairs of socks. I'm not complaining at all; we get enough hot weather in Chicago during the summer so I won't be trying to get a tan in England or anything. I just don't want my first excursion to be to Marks and Spencer for some warm clothes.
Cost - It is generally more expensive in the UK these days, so I must refrain from walking around Asda screeching "How much?" and "Have you seen the price of this lettuce?" every five minutes. Ditto when we stop for a cup of tea or a glass of wine in London.
Service - is generally slower that what we get in the US, again, not necessarily a bad thing. I rarely complain about the pace of the service, but the American husband and kids have to be kicked under the table as they comment (loudly) on the snail's pace. I have been known to complain about the quality of the service, and shall continue to do so if the situation merits. Like the time several years back when a waitress got all huffy with me because, after she announced she didn't know what the soup of the day was, I asked if she might go and find out. Honestly, you'd have thought I was asking for a complete list of the ingredients, (which is not unknown in the USA).
Food - despite a global reputation for crap food (which these days isn't even warranted), I will be having my fave foods on a daily basis. Ham and Pease pudding sandwiches on stotty bread*, really good fish & chips, Branston pickle on everything, and anything from Greggs. Well, perhaps not Greggs' stuff on a daily basis or I won't fit in the plane seat on the way back.
*stotty bread - is the most delicious, light and fluffy bread concoction and cannot be found anywhere else. At least not in these parts. They're quite large and round, so you'd only really eat a quarter at the very most. Slice it through the middle, butter it and fill with delicious things like bacon, chips (as in fat french fries) or, as I said, ham and pease pudding.
Mmm, Mmm, Mmmm.