Hi ncam!
Courses don't have a relaunch button or function. If you'd like to continue where you stopped last time, you can just log in the same way you logged in before. Alternatively, here is the direct link. Once you are in the course, you will then click on the progress bar (top right) to see which pages/activities still need to be completed.

Hope this helps, please let me know if you have any further questions.