Britain in January?

It's a perfectly fine time to visit as long as you understand that the weather isn't great and specifically there is not much daylight Sunrise on 7/1 is 7.04 and sunset 16.23.

it's not really a great time to visit rural areas in the UK - short days, colder weather and many attractions are closed. But a tour of cities can be very productive.

It depends where in Scotland you are thinking of going. I'd be cautious of Highland Scotland at that time of year, due to snow closing roads, including/especially the A9.
In fact I have just been told an hour ago of snow gates being closed, not sure where, in Aberdeenshire due to lying and forecast snow conditions - and this is only end November.
In the Central Belt you should be all right- Glasgow/Edinburgh/Stirling, but be flexible, just in case.

Have visited in the Deep Midwinter, and thoroughly enjoyed it!

Banish all thoughts of breezy sunshine and happy tourist pix of flowers on a glorious day - but do prepare yourself for atmosphere up the wing-wang.

It does get dark pretty early, although IMHO it rarely gets horribly cold. But part of the beauty of the British Isles (again, IMHO) is how wonderful it looks in low light, with scudding clouds and sunbreaks. There's almost nothing cozier than a pub after a brisk walk through the fenlands or across the Downs.

Good advice already given here about sticking to towns and cities, to avoid getting stuck in bad weather on sodden tertiary roads. It is perfect museum weather - perfect theatre weather - perfect shopping weather - and, as above, perfect pub lunch weather.

You will also be avoiding a wodge of tourists who would otherwise probably be in your way, so that isn't bad, either. ;-)

We almost always spend some time in the UK over December and January, and love it, including the weather. Part of the attraction is it's so different from Singapore's tropical warmth! We actually did a week in the Cairngorms over Christmas and NY a couple of years back, and had a great time - stayed in a lovely pub with a roaring fire, and did some great walks. Only downside was the short days, and the paths were heavily iced for a couple of days. A little bit of snow as well, but quite manageable.

I normally am in the UK for work in February as well and again, in my mind a perfectly good time to travel.

This is tangential, but here is a link to a live webcam at the snowgate on the A93 at the southern entrance to Braemar national park. It's updated every minute.
Right now: a dusting of snow on the ground, but the gates are open.

I love checking this webcam frequently and daydreaming of travel. And yes, I'd go in the winter!

https://braemarscotland.co.uk/snowgate-webcam/

I originally read your post as visiting London (no idea why). So the sunrise and sunset figures are for London. The equivalents for Inverness are 8.55 and 15.51.

Stacy, thank you for the webcam link. I am booked for a course in Scotland next November and am wondering about the weather then :-)

I've managed to find out which snow gate is currently closed- it's at the Lecht ski area. One of the usual suspects. It is a ski area for a very good reason.

The snow there looks like it might almost be ski-able.

I don't think they all have web cams- notably Drumochter on the A9, Dunbeath on the A9 north of Inverness, Carrbridge and Dalwhinnie (both just off the A9)

It’s not really true that the museums in London will be deserted in January. London is a huge city with a population nearly 10 million and people visiting for lots of different reasons. It is ALWAYS busy!

I imagine the British Museum will be crowded, just not quite as crowded as in the summer. I heard from both a staffer there and a tour guide that weekends and holidays are busiest. Foreign tourism is generally unaffected by the day of the week; it would be locals or near-locals in the city for a day who'd make Saturday, Sunday (and maybe Friday to some degree) busier than other days. Locals are probably about as likely to visit in the winter as in the summer. For what it's worth, I was also told the Museum is busier on rainy days.

Thanks, Everyone - much appreciated!

I'm in Aberdeen now. It's cold. 25 degrees F. January will probably be colder. Not a bad time to visit. Just dress warmly and be aware it gets dark early.

I arrived today at about 4 PM and the sun was already setting.

London will be crowded but not summer crowded.

Go and have a good time.

We booked it! We're going the last two weeks in January and I can't wait!