I have to agree with Jannie. And I have yet to make a quilt from a kit that I haven't had to buy more fabric for--and no! not from cutting errors.
I bought one with a adorable panel from Keepsake (of all places) and the backing was 6" too short! They offered to let me return the kit. At that point I had it made, but they didn't offer to send me more fabric for the backing. Grrrrr.
Be careful with kits.