I believe what I am getting is the beta and they have being giving out codes to the alpha.
Unfortunately no email giving me a code to the alpha :/. However this appeared… (browsing at https://www.epicgames/fortnite/en-US/home)
Foolishly I clicked download and it helpfully re-installed my epic games launcher. Such a tease.
Maybe I could plead for a code on the basis that I have bought the beta. I understand the actual release is sometime in 2018.