Great news about the email!
Is there anything about the application that has you worried? The visa is a tick-box application. If you tick all the boxes, you get the visa. Did you submit the required documentation? Do you meet the requirements?
If so, it's probably just a timing issue that the fee hasn't come out (though a bit odd, I'll admit). You'll know very soon. Hopefully the extra holiday mail won't delay the package in coming back to you! Keep us posted!