Considering doing an LLM in this area is a good idea. At Ince & Co a lot of the lawyers have done so. I don't think it would be a good idea to get hold of those books if you haven't started your degree though. Firstly, they are very expensive and are unlikely to be found in a libary near you. Secondly, and importantly, if you haven't studied basic contract law yet- you will be putting the cart before the horse.
Either or both of these reasons could result in you losing interest in the area sooner than you think which would be particularly distasteful to graduate recruitment at Ince & Co who place a lot of emphasis on their applicants having strong academic history.