As much as it seems to be a nice idea, its going to be very difficult. First of all if you are planning it for the summer period you should have planned and talked to correct people long time ago. AS you know Cypriot mentally is anything but speed
First of all about the Turkish band Pentagram as you might have noticed they are Turks, and for a turk to enter the south side he/she needs schengen visa, its not really an issue of talking to the correct people but applying and getting the visa beforehand.
If you plan on organising the festival on the northern side, lets be realistic, from a nation who cant even organise a bus from Nicosia to Larnaca properly don't expect something like this
As for the UN, they will not be fucked to organize anything, as you have been told.
My suggestion is talk to a municipality such as the Strovolos one and have a music festival like with had two year at the Acropolis park. Greek and Turkish bands, everybody spreads the word, give adds to the newspaper. done everybody happy. I suggest you contact EDON as they are the youth organization of Akel and they do organize things as such
I have a few contacts from Akel and EDON, if you need my input i am more than willing to help

