When it's your time, she'll find YOU, my friend LOL I don't mean to be cryptic, but IME when I've looked and looked and looked I usually turn out zippo. She always appears out of the blue for me. Good Luck with your search!
EDIT: And do you mean London, England or London, Ontario, Canada?
Come to wales bro and id sort you out :/ But yeah londons massive surley you could find some.. ask hippies innit haa.. go to like camden if you know where that is, ive had tabs from a party up there once, but ask around