England in May

Where are you going to be in England?

Northern or southern England. London can be hot during August and facilities like the underground can get hot:
https://en.wikipedia.org/wiki/London_Underground_cooling

The B&B hotels that we use were also not cooled with "air conditioning" units.

Take care to avoid Windsor during the great occasion and you will be fine.

We will be traveling all over, we're renting a car and planning to travel to northern England/lowlands Scotland during the wedding. We'll be in London afterwards.

Agree with Norma. If you stay out of Windsor for the couple of days around the wedding, you should not be impacted in any way. This is not as big a deal as the wedding of the Prince of Wales.

I'd definitely recommend visiting in May rather than August. Not only will the main tourist areas be very crowded in August, it's just no fun if it's too hot.

so you'll be 200-300 miles away when the wedding takes place?

Yes, we're planning to be far away from the actual wedding.

As far as weather goes, we live in southern California. It routinely gets over 100 F in summer. Unless it's 90 outside with high humidity, we're fine.

Are attractions busier in August generally? Not just in London but around the country.

I would choose May because of the flowers being in bloom, and the times I have been there it has been perfect, weather wise, for touring England. If you get a chance spend a couple of days in York, there is much to see and do and it is just a nice place to spend time.

English bluebells: Mid-April into May.

Forget August. May, hands down May if those are your choices. Book accommodations now!

P.S. I'm IN not near LA. Trust me you'll be lucky to see as much sun and have temps anywhere near what we enjoy here in May or August.

Leave the flip flops at home.

There's a much greater risk of distinctly chilly, wet weather than of a heatwave. Unfortunately, you can't be absolutely sure it won't be so hot in August that you'll want air conditioning. At least that shouldn't be a concern in May.

Before making a final decision, you might go to wunderground.com and check its actual day-by-day temperatures for May in recent years. Average can hide some unpleasant realities. Enter Edinburgh, choose History, choose Monthly, then use the pull-downs to select May and 2017. Repeat for 2016, etc. 2017 wasn't bad at all except for the fact that it rained 2 out of every 3 days in the last half of the month.

May is a good month to visit Britain. We visited Britain after a cruise and rented a car in 2013. It will be a bit chilly, but not bad.

We did a wonderful 28 day drive tour of Wales and England last October. Here is a detailed story of our trip.
28 days in Britain and Celebrity Eclipse home
https://www.cruisecritic.com/memberreviews/memberreview.cfm?EntryID=599139

Definitely come in May as long as it's not the holiday week of 28th you'll find it less busy, particularly at any attraction that might attract UK kids such as Harry Potter Studio tours or Lego land ( not sure if you have school age kids coming). Don't worry about the Royal wedding. Pack a sweater or two.

The wedding is not until October, right? Nothing for crowds to see yet. Security is a good thing.

I was in London the month before Diana and Charles' wedding. The only thing I noticed were the tons of cheap souvenirs marking the event. Which, having selected a few for gifts, have become my only surviving and treasured mementos of that trip.

The wedding is in May. not October, Stan. You are getting your royals mixed up. It is Princess Eugenie whose wedding is in October. Oh, my! However can we survive all this excitement.