Yes, if you call the same javascript function EmailMessage() but this time with he the learner's email in the first parameter, then the email will be sent to the learner's address.

So, I can use the variable stored in Storyline?

When the learner clicks on a button,

var player=GetPlayer();
EmailMessage(player.GetVar('email'),
'MjI3fDM3MDV8OWM4NDUyNGRhNzIwMzM2YzI4OWE3ZmVlMmMzZGE2MjI');

I have tried this out and I used my own email as the test, I did not receive an email though.

Yes, accessing variables through the player is how Storyline works, this should be fine. It doesn't work because the widget with the id you're showing in your example doesn't exist. When you save a new email widget, you will receive a unique code. That's the code you need to use in your projects.

EmailMessage('paul.moody@winslow.com.au',
'MjIyfDM3MDV8Nzk2ODY4YmEzMzQ5NzI4ODcxN2JkNmRmZTQwOWI4YjQ');

Understand, thanks, I have it working now, but how and where do I add the line to send another email to the variable named email? I've added another trigger to do it, but that didn't work, think I'm going to have to send the email to an inbox and set up rules to send it on to the learner as well.

The way you had it:
var player=GetPlayer();
EmailMessage(player.GetVar('email'), 'MjIyfDM3MDV8Nzk2ODY4YmEzMzQ5NzI4ODcxN2JkNmRmZTQwOWI4YjQ');
looks fine and should work (as long as there's a variable email and it contains a valid email address).

It didn't work previously because you had an incorrect id (the MjlyfD... string) in your code.