Checking 00z at T36 shows many of them with low just south of Brest in NW France around 990mb.
Should reality follow I have been impressed with ICON.
Expectation for me is still a few cms. For me we probably would have wanted a slightly more northerly tracked low heading NE up channel and a little more vigorous and as others mention cold already entrenched.
Possible adjustment of Met Office warning then. Amber maybe for parts of Kent, Sussex, Essex. Then yellow still for similar area to before is my thinking.
Anything from 2-5 cm for you I think. Based on current models. Better for those in more Southern parts of this regional thread. Kent etc up to 10cm possibly in a few places.