You need to be registered on the website for this feature. All you need to do is add items to your basket, they will then remain there until you are ready to order. If you close your browser session, you can reload your basket.
Simply log in, go to My Account and click on Previous Baskets. From here you can reload your basket and proceed to the checkout, or carry on shopping.
Your baskets will not be saved for longer than 30 days.