We are scheduled to be in London November 6 - 9, so we'll avoid Guy Fawkes and Lord Mayor's Show crowds, but I gather the area around Westminster Bridge, especially the South Bank, is usually crowded. Will it be crowded on these days in early November?
Bonfire Night is 5 November and I am not aware of any events in central London for this. Many bonfires are likely to be over the weekend of 3rd November, as not many would be held midweek on a school night.
The Lord Mayor’s Show is 10 November, so outside your travel dates, so there won’t be any crowds.