That sounds like a fun night!
If I understand the setting correctly, it's basically a group of ladies getting together for a mom's night out. Unless this is a charity affair, I would book it like any other party.
How many guests you are expecting to read will decide on your approach. When I do parties I usually tell them about six guests per hour, so everyone gets a nice ten minute reading and I do maybe six cards for that. It's a quick reading but long enough that it doesn't feel rushed. Of course you can do shorter readings if you need to. I have even done events where I do one card readings standing up and go through twenty guests in an hour, but this is a different situation.
Two ways I play this. It is either a party where the main event is something other than me, or it is a "Tarot Party" where the main reason for the get together is for the readings.
If it is a party where the ladies are doing their party things and getting readings while that is going on (birthdays, cocktails, etc), I show up and set up in a separate room and have them come in one at a time.
If it is a Tarot Party, I give the group a brief history of the Tarot, ask them about their own 'psychic' experiences (to get conversation going), maybe show them how to use the cards and pendulums and such, and let them play with that while they are not getting their own reading done. Sometimes I set up in a separate room for these parties, and sometimes I set up in the main room and everyone sits around and listens to everyone elses readings - this is the best fun as they will all interact and comment as each reading happens!
For either situation my fee comes out the same. For events and parties I charge $150/hr with a minimum two hour booking, and for Tarot Parties I charge $25 per guest at six guests an hour. The only difference is that at a Tarot Party the hostess gets her reading for free, and I sell my books and such (the hostess also always gets a free gift).
Hope this helps a little.
- Dennis