Novotel Canary Wharf is now taking bookings from 28/11. Some weekend around £100 prices for December.
Get a high up floor and you'll get some great views. The executive rooms on level 30-32 come with
private concierge, additional amenities and a 2 hour (daily) complementary access to the rooftop with drinks and snacks.
Interesting to see they limit the time you can spend on the rooftop, though I can't imagine it'll be too busy in December. Hopefully this will be a nice addition to the area. I live locally but I might pop along and try it out one night.