London is my favorite city on the planet. Each and every visit always find something new to see and explore.
All good advice re: mapping.
For me personally I find it a very walkable city and with an Oyster Card to use on a bus, tube or overground train, very easy to navigate when you get tired. Get a pocket sized tube at a manned station ( harder to find ) but often the map is on the counter. Very useful for route planning. Also review Timeout magazine online. Often you’ll find out about events or places you’d not even considered seeing. Somewhere like the Mercato Mayfair food hall or the Painted Hall in Greenwich.
Besides visiting the must sees you might also consider such intriguing places as:
Leadenhall Market the last glass covered market in London. Easy stroll from the Tower of London. It’s adjacent to The Gherkin so great dichotomy of architecture.
St Dunstons in the East church garden is also an easy stroll from the Tower. Nice place to sit and reflect.
Check the Tower Bridge opening times while your are there. https://www.towerbridge.org.uk/lift-times
Maltby Market which is easy stroll from Tower Bridge and if looking for a traditional pub experience, stop at the Anchor Tap.
Don’t miss visiting Spitafields Market. Great booths and if there on a Friday it’s vinyl Friday. Heaven for LP lovers. https://oldspitalfieldsmarket.com/events/vinyl-market
Richmond Park. It’s huge. Very relaxing spot to counteract the urban sights and sounds of London. Lovely waterside stroll to Ham House. Then walk back and enjoy a pint and a meal the White Cross pub. From Paddington Station to Richmond Station is a 1/2 hour tube ride.
Could also tube to Warwick Avenue Station the walk about Little Venice or better yet tube to Hampstead and follow Flask and Well walks into the Hampstead Heath. If interested arrange for a tour of Highgate Cemetary.
Guess my point is once you’ve visited Parliament Square and Trafalgar Square explore outside the city boundaries. Appreciate the variety of neighborhoods.
I also must recommend a visit to the Museum of London. Helps you understand the evolution of the city you are visiting!
Great city and when travel is once again safe, please enjoy your visit there!