Bring a camera, and a notebook, pencil and highlighter. My first camp, they passed out #9 sharps for the detail sewing and bigger needles for basting and carpet thread. Did you ask Elsie if she will supply the extra? If it is for a fee it is worth it because she also will give you buckles and leather straps, a special canvas; which is hard to get, and lining and all the threads and needles you will need. Also a tape measure with centimeters on it which you will use constantly.
One of those "magnetic" needle pad cases are great and we always sneak in a few pins. Throw in a calculator too.
Since you are driving bring a footstool and a pillow in case you have to sit on a hard chair all day. heck if I was driving, I would throw in my steamer for the motel room.
Anne's idea about the cheater's is true. Since I have been kiltmaking, I have 3 pair of glasses I use depending on what part I am sewing. Kiltmaking has been hard on my 52 year old eyes.I never had to wear glasses before!
Your fingers and your hands are going to be sore, I always have a callus on my middle finger from the sewing needle and when I go to kilt camp it still gets sore because you are sewing 12 hours a day. but you will have so much fun and be learning something that is really interesting. All your classmates will be going thru the same thing. You will all suffer together and that is why we need wine and hot tubs before bed.