Hello,

Based on your description, the dates will do what you intend it to do. The until date can be the same date as the due date and that will prevent students from submitted "late" after the due date. 

I have tested your description myself. If you look at my screenshot you will see in "student view," students will get a message saying, "Correct answers will be available . . . "

I hope this helps.

-MaryAnn