I've just booked our flights for this Christmas. After lots of searching, I managed to get them for £850 with Asiana, which I was quite pleased with. They're at the weekends too, which means I maximise my time off work.
The only thing that's worrying me is the current situation in Korea! The connection is in Seoul and Asiana are Korean, so hopefully everything will have calmed down by the time we depart.
You might be able to get cheaper flights in the period between Xmas and New Year.