You may well be right on copyright law (missed that module during my LLB )
Not sure I understand the comment about "implied terms printed in books".
I suppose you might say that wording in a book trying to prevent resale was not incorporated into the contract to buy the book, and therefore not enforceable, as it was not made available at the time the contract was made.
I agree that if you have signed a contract with BGS which includes some standard boilerplate wording about not on-selling course materials, then this would be an express term of the contract and BGS would have a cause of action against the seller of the notes if it was breached (if they could be bothered).
This would only be against the seller, BGS having no recourse to the buyer of the notes as they are not a party to the contract.