Hi Vassia, I believe the banner as a whole will be linking to the landing page, so placing a link inside the banner itself might not be possible technically.
Greg Varnent is taking the lead on this, so he'll be in a better position to explain the details.
If you can include the link inside the Bulgarian translation of the landing page in some clever way, then that should be fine; whatever works for you, really.
Otherwise you will of course be able to include that link in your communication on social media and to real media. I'll start working on a template of a press release when I get home in the evening.
Thank you for your work on this; I'm very grateful.
Tomasz @ mobile
translators-l@lists.wikimedia.org