Thanks for the comments, i do agree with all of you, that it may be hard or time consuming chasing past students to do my evaluation, so i might just stick to the current students i have. :)
I have just updated my evaluation plan and added a questionnaire as well. The questionnaire is still under development, i am planning to have a different set of questions developed for the facilitators to get their perspective towards the course.
I have uploaded the plan on Google Doc