Usually 'Hey up, me duck!' and it means much the same as 'Hello, my dear!' Hey is just a call for attention, usually expressing joy or questioning, up is just a word added for effect, me is a dialect variation of my and duck is a term of affection, especially in northern England.
If you've seen Wallace and Gromit and the Curse of the Wererabbit, they have a glossy mag called 'Ey Oop' which is their equivalent of Hello magazine!!!
"Me dook" was, and I hope still is universal, in Leicester. if you went into a shop, you'd get "Now, me dook, what can I do for you?". The "oo" is short, as in cook. I don't think there's an origin really for "duck", since the word is so common as an affectionate term. However if the Londoner talks about his old Duch, she's not a Hollander - it's short for Duchess and the term's probably obsolete now.