Met Office Update:
"An Atlantic frontal system looks likely to bring rain into parts of southwestern Britain on Wednesday. As this moves further east into colder air there is a chance of this rain turning to snow. The extent of any snow is very uncertain, but 2 to 5 cm could fall across a swathe of southern Wales and southern England, with a small chance of 10 to 15 cm settling in a few places, most likely on high ground above 200 metres. As the rain and snow clears on Wednesday night there is a risk of widespread ice forming on untreated surfaces."
Looks like it is all very uncertain still, people may get some surprises tomorrow evening but who knows...