Don't be so sure you can't afford to stay. I went a couple of christmases ago, stayed in a very basic hotel and was only £40 for a twin room for the night. Now don't get me wrong, the room was basic at its lowest level, but did the job for just a night. was only 10 minutes walk from a main tube station too. I booked through lastminute.com. You didn't say how many people would be travelling, but just did a quick search on last minute for a random date in january and single occupancy starts at £30 sterling. There's also late rooms you could check out too. It just seems a pity to go all that way for only one day...