Hey Rick,
First off, welcome!
First jam session, I wound up using someone else's rig. It was a Headrush modeller into back side of an amp, and couldn't really figure it out. Owner was helpful though and adjusted things on the fly mid-way through first song.
Second time I brought my own modeller, with powered speakers and it played great with both guitar and bass. So obviously easy to control.
I think you just gotta be able to roll with the punches, and enjoy the experience for what it is.
Wishing you the best at your next Jam!