They're in no way official, so I wouldn't necessarily expect any of them to end up as a cover to the book when it gets published, but they are - I admit - pretty cool.
East of England is being crowdfunded via Unbound Publishing; this means pre-orders of the book are necessary to raise its preproduction costs (editing, proofreading, design, printing, the cover, advertising, promotion and distribution and so on). So, don't wait till it hits the bookshelves! As you'll see from the book's details, there are a handful of different pledge levels with escalating rewards; plus, everyone gets their name in the book as thanks. Plus, you get to be a patron of the arts, which isn't too bad, is it?
Which one's your favourite? And how do they relate to your own visual sense of the book? Again, details - including how to support East of England - are here.