Ideally, what you need to do is get a big transaction fairly close to £50 (like the betting sites giving £40.40 for example) and transfer that to Clubcard points. Then just use the site for normal shopping to make up the balance before the end of the year. It can build up quite quickly.

An album on iTunes returned about 40p, and the scan and save is useful too. I just got 50p back for some Milk that we'd bought anyway and that one has paid out already and the clubcard points have been transferred.