I have reproduced it here quite large to show the features which, to me at least, are important. Your image can bleed off to the full size of the card, and can be overprinted. The data page is a non-nonsense grid of dates- very useful for appointments etc.
What you have got to be aware of is that the files have to be presented to them as CMYK, so be prepared to change each one from RGB to CMYK in Photoshop paying close attention to how your colours do or do not change. And I always specify the highest quality card, which I would suggest is the least one can give one's masterpieces. I also make a point of going through each of the months and editing out text on certain dates that I don't want, such as the Queen's Birthday or Father's Day - stuff that may not be appropriate or needed. After that it's plain sailing. They make lovely Christmas gifts for appreciative family and friends.