Wish I was going - have another commitment.
Impossible to actually give a forecast with any accuracy. A lot of snow developments tend to appear in the short term forecasts but.....
There is a pretty reasonable chance that London will see snow showers. If my experience is anything to go by (olympia last year) trains ran an awful lot better than the roads did under what just might be similar circumstances.
There's also a potential development that just might bring decent snow over friday evening/night too. (no threats/promises - just the possibility)
But there again you might all get nothing at all.