From keel to truck, meaning from top to bottom (albeit in reverse order) often referring to how well one had or hadn't washed

Slower than a wet week = taking an inordinately long time

Not as green as he's cabbage-looking = not as clueless as he's trying to pretend.

As popular as a pork chop in a synagogue (often, these days, with mosque instead of synagogue) or as popular as a fart in a bottle or as a fart in church

Shake a leg (or) Unwrap your rung = get a wriggle on = hurry up!

Variations on some above
"I see it all", said the blind man, when he really couldn't see at all.

Bright as a new pin

Queen Anne front and Mary Anne behind ; more or less equivalent to "Not as smart as it looks" but also to "All fur coat and nae knickers"

More trouble than a barrel of monkeys

Cheers, Rowan