When something is worth its weight in gold, it is extremely valuable.
If you pull chocks, you get ready and leave a place.
An idiom primarily used by those from the North East of England, used to emphasize the fact that children who fail to ask for something (usually from an older person) probably won't succeed in obtaining it. (bairn = child, nowt = nothing)
If you know something from A to Z, you know everything about it.
If you have a riot, you enjoy yourself and have a good time.
You pays your money and you takes your choice is used when people have to make choices that could result in them winning or losing- it is their decision and responsibility.
You pays your money and you takes your chances means that when you do something that involves a risk, you cannot control the outcome, so you may win or lose and should accept that.
Stone the crows is used to convey shock or surprise similarly to "Oh my God".
"Stone the flamin' crows" is a more emphatic form of the expression.
Someone who's as flash as a rat with a gold tooth tries hard to impress people by their appearance or bahaviour.
A wildcat scheme is rash - financially or ethically - and will probably fail.