There isn't an English translation out anywhere yet (as far as I know), and I doubt there will be one anytime soon.
As for whether its NaLu or GraLu, apparently it is split into 6 stories/scenes. The 4th of which is entirely GraLu; and I have heard that there is NaLu in the light novel, but I have no idea at what point.
I was searching for at least a summary of the light novel, but was unable to find one in English. So if you want to use Google Translate:
link
BTW, the novels events take place after the Edolas arc.
