Set up a shortcut to insert a symbol

Despite living in the UK I am hard-wired from some years spent in the US to use a US keyboard layout. One problem for me is that these keyboards do not have a £ symbol on them. On a Mac, I can insert a £ using OPTION-3 but not in Emacs since I have OPTION set to META. This is easily addressed with a bit of code

(define-key global-map (kbd "C-c M-3") (lambda () (interactive) (insert "£")))

Now C-c M-3 will insert the £ symbol. N.B. I could have just bound this to M-3 to match the behaviour elsewhere on my Mac, but I already use that for something else!