An appositive is a noun that follows another noun in order to provide more information about the noun.
With regards to the question, the appositive is "a chivalric utopia". Here, the appositive is used to modify the main noun which can be found in the last part of the sentence that is, Camelot. It gives more information on Camelot.
Blanca Flor and Juanito will probably be reunited later in the story. After all Blanca does to help Juanito escape, it is likely that he will find help and return to the farm to save her. He would not leave her there to be punished after she saves him and helps him get free.