If you have previously recommended this thread, you should see a tick / check mark on the recommend button. Click the tick to undo the recommendation (the tick may appear to change to a cross as you do this.) If you added a comment with your recommendation, you will need to delete that from your facebook wall separately.
Walk along the South Bank and see all the street performers. The London Aquarium The Royal Festival Hall (on the S Bank) always has something going on in or around it, there are loads of Christmas Markets on the S Bank, and a branch of Giraffe, child friendly restaurant.