I hope to do a trip report but want to put this out there for anyone visiting London soon.
Allow lots of time for the Tate Britain's special exhibitions. I often thought "I must be at the end of the exhibition" then discovered another room, then another...My Tate visits were highlights of my trip.
My husband and I just returned from a 17 night holiday in England. I was eager to see the John Singer Sargent special exhibition at the Tate Britain, but I ended up spending much more time at the museum than I expected. We arrived at the Tate and began in the free collection. I spent most of that time in Turner gallery before we stopped to eat in the museum cafe (perhaps 2 hours of galleries before eating).
My husband went on to see more of the general collection before walking and waiting outside. I decided to purchase a membership. The cost of the 2 main exhibitions was about half of a membership. I hope to return to visit at least one more time in the next 12 months. I spent at least another 2 hours just in the Sargent exhibition (60+ items). I read almost all the information, listened to several of the QR coded recordings (2-3 minutes--only a few of these) and I took photos of large information boards, some paintings and descriptions. I'm not a slow reader-- but I didn't shortchange myself on the special exhibitions. I allowed myself time to enjoy the works and take in the details which included history relevancy and curiosities. If I lived in London, I would return even to the special exhibitions.
The next day, I returned to see Now You See Us: Women Artists in Britain 1520–192. (150+ items). It is excellent. Again, I read most of the information and took photos. My phone died so I took a break from the exhibition to grab some soup (and the kind members' assistant charged my phone at his desk.) I spent at least a couple of hours in the exhibition and close to an hour in the lounge. There is so much more I wanted to see at the Tate Britain---and that doesn't include anything available at the Tate Modern.
https://www.tate.org.uk/whats-on/tate-britain/women-artists-in-britain-1520-1920
https://www.tate.org.uk/whats-on/tate-britain/sargent-and-fashion