Required and Recommended textbooks are listed in your Unit Outline. Check the details, especially the edition listed. If you are not sure, confirm with your convener.
Buy new textbooks -
Check prices, as there can be significant differences between suppliers. Check if estimated delivery times are listed.
Buy or sell secondhand textbooks
There may also be specific discipline orientated social media groups - places that you can buy or sell secondhand textbooks - ask around within your discipline.