A couple of people (Windsor Pilates and Btimbit) mentioned they are coming to London over the next few months. A few good suggestions have been posted - the Museums are fantastic, free and lifesavers whenever there is ####ty weather.
One thing that does get overlooked is the Gondola over the Thames between Royal Peninsula and North Greenwich. Essentially, it’s like taking the Gondola at Sunshine, but over the Thames. If anyone visits with kids, I always take them on that. You get excelllent views up and down the river, see planes take off and land from the City airport and can take in the O2 Arena and all the restaurants there.
If your kids are over 10, you can also book a climb up the O2 roof.
The gondola is reasonable - £6 each way for adults and half that for kids.
https://tfl.gov.uk/modes/london-cable-car/
Climb the 02 -
https://www.theo2.co.uk/up-at-the-o2/climb
For Winsor, you may want to do the Emirates tour. They have guided tours led by an Arsenal legend for a bit extra - again, you’d need to book ahead for that. I had my tour with John Radford and it was really good. I’d love to do the tour with Perry Groves.
https://arsenaldirect.arsenal.com/tour/tour-type/legend