Hey Katy welcome in.
There is a wealth of info in here on figuring pricing, here are a few links...
But basically you would tally up all your costs, food, kitchen rental, fixed and varialble costs,
like travel etc, then add in your labor-- helpers, your own (including planning, shopping etc) .
Last, add in your desired profit, (separate from your own labor) divide that total by number of
prople to get a price per person. Once that's done, research a little to see if that's high or low
compared to the "going rate" in your local area. and adjust as needed.
Its only 30 ppl, you sure your kicthen's too small?
How many menu items are you offering?