ok.
I think timings for this front are still up in the air. I've a gut feeling that the front will be slower than currently programmed in by gfs. I don't have any concrete evidence of this though, so could be wrong!
I think that it is possible that we (any of us) don't get a huge amount of snow from the front crossing itself. I think that for most there will be a fair bit of rain first (which is bad news for gritting) then some snow on the back edge before it all glazes over. nasty. Then for many, esp in the west including Wales and SW there will be heavy snow showers piling in snow on top of the ice. How much snow people get in the initial period as the back edge of the cold front goes through - well who knows? anyones guess really.
If you are choosing between travelling thursday day or friday day, do it thursday. Thursday night - decision is more problematic and I would listen to local radio and look at the traffic england website for realtime flow on motorways.
I think that once this weather kicks in, then our travelling fate lies in the hands of the highways agency and local councils!
Piratecat, Saturday/Sunday could be a problem for the kent area. Its a tricky little low that is difficult to model with any accuracy at this range - but worth being aware.
I think that hopefully if you are flying from heathrow or gatwick on friday, that as long as you can get there ok then you should be able to fly. But please check!!!!!
GentleOtter - if you could hold them for me until the Spring that would be great 
Whoever asked about where I get my info from. Mostly Wetterzentrale but I do cheat if it is getting tricky and wander round various weather forums to make sure I'm not missing or misunderstanding stuff. Close to the time (within 24 hours) met office invent can be great for timing of stuff.
Right, back later :)