hi
Please could anyone let me know if it is possible to change the module template later on, and if so how?
If it's not possible, how do you lift all the content from one course (with another template) and put it into a new course (with the correct template)?

Not sure that you can globally change what you have already that easily but you can insert another later.
You might need to search and replace the existing references and components in the xml to make a global change.