I saw that convention goers are getting a special doff and title for attending the Destination London convention. I really don't care about the title but I am a DOFF collector so will the regular population of the game have an opportunity to get Leeta? Maybe as one of the rewards for testing Season 7?
The current plan (which could change) is that this DOFF (and title) will remain a special reward for players who attend a Star Trek convention -- watch for news and forum posts in the future as we'll try to offer it to attendees, in some way (through Twitter, the forums, etc.), of the conventions listed here.
Some STO podcasts and radio stations also seem to have a few extras that they've been giving away as prizes to their listeners.