Just email dates when you are available, and suggest an appointment is set up via Outlook. Phone them up first if you like to say that this what you intend to do, as the email doesn't just drop out of the sky. Put a read reciept on the email so you know it's been opened. Any details on the offer shouldn't be discussed over the phone. A prelimnary meeting should happen first to see if anything further can be discussed in any detail. This meeting won't take long, and starts an open dialogue from the outset.
I have worked on partnerhsip projects for years, and this is pretty much how it happens most of the time - Let group members know what is happening at your end, the other parties will do the same (in writing), and agree an initial agenda with the participants... although I may be shit at my job of course!
Edit: meeting is minuted, but these remain confidential between attendees. Nothing to stop a press release, but only if the contents of this are agreed by all (that's if you can get that far of course).