Day 1: Welcome to London
Light walking: 2–4 miles throughout the day on mostly level terrain.
Day 2: Westminster and Whitehall
Strenuous walking: 2–8 miles throughout the day with lots of hills, stairs, and uneven terrain.
Day 3: The Tower, The City, and St. Paul
Strenuous walking: 2–8 miles throughout the day with lots of hills, stairs, and uneven terrain.
Day 4: East London and the Churchill War Rooms
Strenuous walking: 2–8 miles throughout the day with lots of hills, stairs, and uneven terrain.
Day 5: Historic Windsor Castle
Moderate walking: 2–6 miles throughout the day with some hills and stairs. Train: 2 hours.
Day 6: Borough Market and the South Bank
Moderate walking: 2–6 miles throughout the day with some hills and stairs.
( above from the "Itinerary" https://www.ricksteves.com/tours/england-scotland/london)
You can opt out of any activity if you wish, just be sure to tell the guide and your 'buddy' that you are skipping out
The airline you choose will determine which airport you will use.