I think I've found the most Christmassy place in London! If you find yourself doing last-minute Christmas shopping on Oxford Street (good luck!), then I highly suggest you pop into Kingly Court on Carnaby Street to get away from the hustle and bustle.
As far as I can remember, this little complex has always hosted an array of little indie shops, but now it seems to have been mostly cleared out and turned into a foodie paradise. From the ones I've tried - Cha Cha Moon, Pizza Pilgrims and Shoryu - to the ones I haven't - Señor Ceviche, The Rum Kitchen and Whyte & Browne - I think it's safe to say there's something for everyone. And the Christmas lights are pretty darn good, too!