London in 3 days?

It’s very doable. I used to do quick hit, Thursday to Sunday trips from London to New York to go shopping back when the exchange rate worked in our favour!
The only minor negative for your trip is that I always found the jet lag heading east was worse than going west, but you might be different?

Nowhere is that far from anywhere else in central London so book a hotel near the centre and you should be good.

3 full days in London is better than no full days in London. However, have you considered a 5-hour time difference and jet lag? That could eat into your full days. Have you made a list of the highlights you want to see? Can you squeeze them all in? One great thing about London that time if year are the Christmas lights. London does it like no other.

One can see a lot in 3 full days especially if you don’t mind being on the go much of the time. Since the flight will probably arrive early to late morning, one can even see a lot on arrival day. Drop your bags at the hotel, then go for a walk around whichever area you’re staying in. What you don’t want to do is sit still for very long or take a long nap upon arrival.

Plan out the places you want to visit by proximity to each other so you’re not wasting time going back and forth across the city. London is very walkable. For example, the Elizabeth Tower/Big Ben, Parliament, Westminster Abbey, #10 Downing Street, and Churchill War rooms are very close to each other.

Lots of highlights can be packed into 3 days, or still several sights and experiences, if you don’t try to cram in too much. Bring enough warm layers, though.

We had 3 nights (2 days) in London just before Thanksgiving last month, then 3 weeks in southern Italy, followed by 9 more nights in London. We’d brought warm clothes and coats, we thought, but left our long underwear tops and bottoms at home. Well, London was surprisingly cold - very windy, and humid, with a bit of rain. We then bought long underwear at a Uniqlo store in London, expecting to need it for our return in December. It actually poured rain in Italy, though, and it was nice to get back to London for the “balmier” weather.

So London in mid-to-late November was unexpectedly extra-chilly, and an extra layer or two will keep you more comfortable than if you pack just for “cool,” not “cold.”

I have done multiple trips of this duration (usually after finding a cheap airfare somewhere) and enjoyed them.

Yes it’s very doable. Many people here take short 3-4 day trips to New York, although less so these days as it’s so expensive there now for us poor Brits.

The key here is to really identify what is important to each member in your group and make sure the top choice from each person is included in the agenda. Then add in other items of interest.

The fact that there was a cold snap in late November this year is no guarantee that there will be one next year. Since then it has been milder than normal for several weeks and we are now about to have another cold snap. Next year could be completely different. The only advice anyone here can give you is to prepare with plenty of layers. I would not pack thermal underwear - I don’t own any myself.