Hi @Fawleyeventmanager Kathryn,
From what it sounds like, they’re wanting to invite you on as an interview subject rather than just a straight up advert? (Adverts are usually just 30s or so of course), so if they’re inviting you on live then it certainly sounds like they’re giving you a slot, which is ideal.
If I were you, I’d make a list (something you’re bound to have already of course) of all the event’s key features/details/benefits etc, speak to the station ahead of time to say this is what it’s all about, then if they’re planning on asking some questions they can plan those ahead of time so they know the right kind of questions to ask, to give you the maximum impact possible on the day of the interview.
(Or, depending on their level of proactivity, might be worth you writing your own questions to ask yourself, which can be fed to the presenter ahead of time; so at least you are fully prepared and can have pre-planned answers to your own questions.)
Radio can be incredibly powerful in rallying the troops (no pun intended) to gain maximum attendance etc, so this is an absolutely superb opportunity to exploit.
If it’s not so much an interview but just a ‘x’ min slot for you to promote it directly, then I would just treat it as something you might say at a business networking event - work on an ‘elevator pitch’, however long they’re giving you; and just reel off all the key points about the event and why people should attend, what’s on offer, the cause it’s for, what people can expect etc etc.
Hope that helps. If you need anything else or get told some more detail about what to expect from the station, just drop me a message, happy to help.