As mentioned above, can you take some sort of handwork project? And I suggest that you go! Try it! You have nothing to lose, and may make some great friends. You can get a feel for what happens at these gatherings. Then decide if you'd like to further this adventure. Best to you!

You could plan ahead, as quiltstrinz implied, and have your next project ready to sort and cut.
Other things would include finishing binding a quilt, putting on a label, rewriting directions so you can follow them better [something I do a lot!], or any handwork.
I have yo-yo's ready to sew and some embroidery.
There is always something I can take. If worst came to worst, I could take quilt magazines and mark the ones I want to save on my computer for later use.

I have a " go-to" kit at the ready...it's hexies for my " takes forever" GMFG...has scizzors,thread,etc. You could also take a rotary cutter,ruler,mat ,and a " collection" of scraps to cut into organized blocks for scrap quilts. Just go,enjoy the day,have fun.

Any of the suggestions above will work.

I have a church group of sewers that meet twice a month. I bring anything that doesn't require my DSM. I will bring a small mat and cutter and cut squares, or like I did yesterday, I was cutting 2.5" strips for making a Strip Tube quilt. I have also brought a quilt that needed the binding to be sewn. Great to take those hand sewing tops too like Hexagons.

Our little church has a group that meets on Tuesdays, and I try to bring something that does not need a machine. I can't quite see myself dragging it there for just three hours.

after you get the feel for the group, see if you can bring a machine and leave it there. that's what I do, so if I need the machine that week, I have it there.
Otherwise, I bring something to hand quilt. good luck, let us know what happens

and bring something finished for show and tell

The one I used to go to on a regular basis everyone brought a machine - I was the only one hand sewing. It was my first exposure to the thrill of featherweights. When we did the Linus Project work, they loved having me there because I did the majority of the hand work on the quilts no one else wanted to do. When I did take my little machine, so many people commented that they had no idea that I had a machine or knew how to use one since they had only seen me hand sew.

Since so much talking goes on during the day it is easier for me to do the hand work than machine. I have a tendency to be rather chatty and it is such fun to get together with a group of people that love to quilt as much as I do and also love to talk about it.

Your charm packs are a great idea. I frequently go sew with friends at other places. It seems easier to me to take a "stage". Either cutting, sewing or binding. I have even taken hexies to work on. (Now that was easy). I have a smaller machine with a sort of to go kit to take that I have in the car but I don't always take it in. It's there just in case I decide to do something different. What I don't want to do is take everything, and set it up for 2-3 hours.