I was put off this competition because it's not just about the quality of the book. Getting on the shortlist also depends a lot on your marketing ability, about the judging of the competition, it says: each Book will be rated based on the commercial viability of the Book (including, without limitation, with regards to the Book’s sales, borrows and customer feedback)
But if you're planning to publish anyway, then you've got nothing to lose by having a go. Good Luck!