Hmm never been to a planning for pregnancy night, the only comparable thing I've heard of would be BellyBelly's Birth Options session! Sounds like it could be good - although keep in mind that if it's run by a doctor the information may possibly lean towards a medicalised way of seeing birth.
Do you think it will be a 'ways to prepare your body and family for a pregnancy' night, or perhaps a 'have a baby at our hospital' night? Either way, hopefully you will learn something useful if you go!

All the best with trying to conceive!