Dannie,
What was the conversation like? Well, it's, "Hi, I'm Helen" then introductions all round then it's things like, "This is the first time I've ever met fellow crossdressers, have you been coming here long?" It's that sort of thing.
I exchanged my story with theirs. Were they out to family and friends, how long had they dressed, do you go out anywhere else. The conversation was just like minded people politely chatting, discussing a shared experience. Don't forget, you'll be talking to people who will sympathise with your situation.
I would say, don't over think it. You will be nervous, that's natural but as I said above, that nervousness rapidly evaporated. I would advise not to over dress. Demure is better that diamanté. That said there may be some dressed to the nines but in my experience most are dressed to blend.
Just for info. My first experience was at a group far away from home. I'd emailed the group secretary in advance just out of politeness. The group meets in a private room in a hotel which meant I walked across the foyer's marble floor with my kitten heels clicking away. I can remember standing in the doorway of the room and hesitating for a second or so. As I say, 5 minutes later totally relaxed.
That night was a real milestone in my dressing journey. Being able to talk face to face lets you know you're not alone, not weird, just you and that's okay.