I'll be spending a weekend (Fri, Sat and Sun) in London at the end of October before heading to Portsmouth for work. Anywhere to avoid (crowds / closed), or any tips for a weekend visit?
Sure, stay away from Parliament Square, the Tower of London, Westminster Abbey, Portobello Market. Virtually every "site" will be opened. What are you looking to do besides avoiding crowds?
If you want to avoid the crowds, stay away from the well known street markets and get to the parks, a walk along the river or Kew Gardens. however, if I had a weekend in London I would definitely want to see the sights- trafalgar square, piccadilly, Westminster Abbey and St Pauls. Also any of the Museums that take your fancy. I would probably steer clear of the London Eye. In really good waether try some of the riverside pubs- hammersmith, Strand on the green or further upriver. Great atmosphere
Be sure to check the TFL website for weekend engineering work on the Underground, Overground and DLR.
The main shopping streets Oxford Street and Regent Street are always very crowded all week. So avoid these. The City is not so crowded on weekends since it is mainly a financial district these days. However this also means that a lot of things will be shut. However St Paul's Cathedral and the Tower of London are both in the City, and the tourist oriented businesses near them should be open.
It depends on what you like to do. If it were me, I'd head for some of the art galleries- the National Gallery and The Portrait Gallery are both near Trafalgar. Tate Modern is over by St. Pauls and the Millenium bridge. tate Britain is not far from Buckingham Palace. Weekends in October will be quieter than other times in the year, I expect.
Just stay away from the shopping areas.