[[http://www.selfridges.com/en/Whats-On/Events/London/Santa?s-Winter-Wonderland-At-Selfridges-London_Santa?s%20Winter%20Wonderland%20At%20Selfridges%20London/?brdcrmb_trail=WhatsOn%7CEvents&rssLink=false here]]. They just opened today, and I think all the dates are still available. It's 7 pounds for adults and 3 for children.