ok - some timings. The timings are likely to vary from this so please don't plan things too finely! also I or the models could be very wrong!!!! Borderline snow/rain situations are notoriously difficult to get right accurately. They can give a lot more rain or conversely a lot more snow than expected.
At the moment though GFS and UKMO look quite in agreement to start before they start diverging later in the period.
To summarise the situation, we have a warm front moving in from the west. Ahead of it is a lot of precipitation which will in general start as snow and then as it moves across the snow will become rain.
This evening: western-middle Scotland and NI
Midnight - Western Wales (some lighter snow through central Wales) Maybe rain or snow in far SW. Unsure which.
Dawn Monday: Heavier snow through nothern England, lighter snow anywhere away from SE and EA
lunchtime Monday: GFS shows it retreating west a bit! UKMO does not.
Monday evening: GFS shows across the whole of the UK (maybe some exceptions in Scotland for a bit?) This is when the UKMO shows a bit of a retreat of the precip back west!
Monday midnight: some reprieve in nothern and western Scotland maybe. maybe not. Heavy snow for central and western midlands and Wales. Generally possibly quite snowy elsewhere. UKMO shows it not reaching the north east yet.
Tuesday dawn - Precipitation everywhere. Much of it snow. Particularly heavy in the midlands and north SW beginning to look positively too warm for snow.
Tuesday lunchtime - This is where it gets tricky for me. A lot of heavy precipitation. In the NE snow. SW rain. Elsewhere, I am really unsure.
glitternickz - I think there is a reasonble chance of some snow for you early tuesday morning, but the upper temps are quite marginal so not sure.