How to access WC()->cart in CF7 hook wpcf7_special_mail_tags

I have created a page that allows users to request a quote based on Cart contents, in the wpcf7 hook wpcf7_special_mail_tags() I want to get the cart contents and return the output (cart items), but WC()-cart appears null in this hook, I cant work out how to get access to WC()-cart in this hook.

The wpcf7_special_mail_tags() works fine and inserts other data into email, I just want cart data though.

Thanks for any help.