Sure, don't panic.
You have a couple of options depending on the size cake you need.
You can either bake 2 rectangles and carve them to look like an open book and (place them side by side) or bake one large 11X18 and carve that.
You can do this, no worries.
It is possible with side by side sheet cakes then you have to carve them. The easiest way is to carve them with a pattern placed on each side (top and bottom of each page) so that you get the same curve all the way across each page. Then use the same pattern for the opposite page.
Good luck.
Just a thought, not sure where you are, but I've seen those pans recently at TJ Maxx...
You don't say where you are but I am in Indiana... I have the pan if you want to borrow it.. pm me 
I stopped using the shaped pan when a customer ate the thinner edge of a cake and complained that it was dry 
I stack 2 rectangles, make a pattern for the curved edges, and carve. No more dry edges!
HTH
Rae
It's not the easiest pan to work with, I have one and haven't used it in 10 years or more. BlakesCakes is right by the time the middle gets done the thin edges are hard and dry. You would be better off carving it. But if you not comfortably carving sheet cakes, you could check Hobby Lobby or Michael's near you they would probably have one.
HTH
Lynn
don't worry about it, it can definatley be carved out of a rectangular cake with a serated knife. And you can actually get a nicer shape buy doing it yourself.
Start with cutting out the center first, i found that the best place to start.
Hope it goes ok 
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