Pace of Meals in London? Also, breakfast suggestions?

Unrushed.

Pancakes like your kids enjoy in the States will be similar but not the same in London though I suppose you could try McDonalds.

Bill’s has pancakes.

https://www.timeout.com/london/food-and-drink/pancake-day-restaurants-serving-pancakes

EAT, Pret, and Leon are all good options for inexpensive and quick breakfasts. There are a few other similar chains. There are also plenty cafes where you can get a full English or other breakfast items. For something different, people like Dishoom’s breakfast and it’s easier to get seated at that time of day. Can’t help on the pancakes as I’m not big on sweet breakfast foods myself!

I would say the pace of meals is "normal", but I am English, so that is a circular definition. I would say nearly as leasurely as French meals. You will not get the bill until you ask.
In pubs, you order at the bar, and pay there. No table service.

Pancakes are not normal breakfast fare. Do not expect them at hotel breakfasts, or most other locations. You may have to search.
Many cafés offer an English breakfast, which is bacon, sausage and egg, plus baked beans, with tea or coffee, plus toast, butter and jam or marmalade.

I'd agree with others that service in London is pretty European and that the waiters will leave you alone until you ask for the bill.

As for pancakes-as more restaurants are doing "brunches" nowadays you can find pancakes though they may be a bit posh. Timeout lists a few of the more trendy eateries.

One that is pretty popular is the American-style https://thebreakfastclubcafes.com

Where are you staying? A lot of the time breakfast is included. If you are staying at an apartment; just stock up at the grocery or deli or bakery. Shopping malls near underground stations have lots of food options. The street markets have food and cafes. There are breakfast buffets in some hotels that are open to public. London also has many of the same or similar fast food places we do. Check the money exchange to see if you are paying a similar amount that you would at home. It was twice as much as what we paid at home when we went; but sometimes you just crave a burger. They do have pizza that is nearly the same. We avoided going out to dinner in fancy restaurants...kids won't eat food they don't recognize...so we would buy a pizza or curry or bring a deli chicken home.

We don’t take as long over meals as the French. The coffee shops all offer pastries, granola/yoghurt pots, bacon or sausage sandwiches or porridge. Pancakes in England are thin, 8 inches in diameter and not eaten for breakfast. Caffè Nero, Pret a Mange and Leon all have good breakfast offers.

There will also be many places that will offer a full cooked breakfast with sausage, bacon, eggs, beans, toast etc.

Weekday breakfasts for working folk are takeaway affairs, eaten at desks, as no one has time to sit in a cafe!

You can find American style pancakes in many places in the UK, primarily younger, trendier places, mostly served with maple syrup, rarely with bacon (for good reason in my opinion). As mentioned, the chain Bill's serves American pancakes with maple syrup AND bacon.

Good places for breakfast? It's almost an impossible question to answer because there are so many places. I'd avoid the greasy spoon cafe types, the cheapest, nastiest food. Dishoom has gained a reputation for making a great Amglo/Indian bacon sandwich fusion but if you want to guarantee some degree of consistency then I'd opt for Bills, at least you get the pancakes.

You can also try le pain quotidien london. They have a great breakfast menu and they fit into the fast casual category where you can have a sit down, but quick breakfast.