When I went through the process of paying for a course (and used the code to get it for free -- that part worked fine, although it would have been better had it not continued to suggest it needed a credit card on that page), it took me to a receipt for the program I'd just purchased. My concern is that it was not entirely obvious what I was supposed to do next to get to my course. I did figure it out by poking at something that looked like a link, and it was, but I suspect many of our users will get frustrated before they'd do that like I did. You should include a very obvious "Click here to go to the course you just purchased" prompt.