Use the card to buy your shopping and then use the cash you would have used for that to purchase the used items.
Do you have a first direct account currently? Are you 100% sure it will allow transfer between credit card and current account?
Just had a quick look and it says transfer to card company and then states you cannot transfer it to members of the HSBC group.
My contribution to MSE. Other contributions will only be used if they cost me nothing.
Due to me being a tight git.