yes...u do need to take buttercream icing to practice shell border, the rosette, reverse shell, rosebud and mum. You also need your flower nail and template for mum. Read lesson 1 to make sure what tips and consistancy of icing you will need. I just finished course 2 last week...your gonna have a blast!!
You don't need much. I just took my class this A.M. I used about 1 C medium. I put about 1/2 cup in each bag because I don't like them too full and I can use different tips. We just practiced the shell border, rosettes and the mum. (I just used white, but you can color it ) If you run short, just scrape your icing off of your practice board and put it back in your bag. Also, about 1/2 cup of stiff ( in a color) for your rosebuds. And a little bit of green thin for your sepals on your rosebuds. Can't wait to start my royal icing flowers next week!!!
You can call the store where your taking your class to, ours always gave us a print out of what you would be needing for the first class of whatever course you were starting. I know you said you wouldn't be able to get to the store this afternoon but if you call, they should be able to tell you over the phone. Just a thought 
Have fun!!
just another tip before you cut your patterns out of your book ( you have to cut one or two the first night but there are more than one pattern for each flower so that is okay.)
I made a photocopy of the page first. Didn't want to lose my patterns.
I took some clear contact paper and sort of laminated the page, then cut them out to be used. This way they didn't get all greasy and gross.
Have fun and take heed of your teacher's warnings about grease free environment cause it really makes your royal icing just fall apart. My trouble came for a small fleck of bc frosting that I hadn't clean off my mixer. It fall in to the royal and ruined the whole batch. So frustrating to sit there in class with your icing just pooling on you nail. ( grrr)
I bought a set of separate disposible tupperware containers to be on the safe side too.
When you get home from class spend a couple of hours cracking out some violets, pansy and leaves. They make great filler flowers around the roses on sheet cakes and cute little cup cake toppers. Mine are like six months old and still good. 
mommachris
If you laminate your templates you will have them forever, I laminate mine with magneton the back and the clear laminate on the top, that way they will stick to your flower nail and you won't need any handy tac on the nail just the template.
Have fun I think course II is my favorite.
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