There is scads of Cockney slang for money. Much of it derives from the designs on the notes - five pounds, ten pounds, twenty pounds.
The first things you gotta learn are that five pounds is a fiver, and ten pounds is a tenner. Then you gotta know the key money values: £20 is a Score, £25 is a Pony, £100 is a Ton, £500 is a Monkey, and £1000 is a Grand.
Here's our list of terms from the dictionary that are money-related. If you've got any more, sling 'em over!