How to upgrade the latest version of photos

I have checked updates & my Mac is all up to date.

Photos can only be upgraded by upgrading or updating MacOS X, because Photos is a part of the system. The most recent version is Photos 4.0 on macOS 10.14.1 Mojave. Is that the system you have currently installed? You are probably running an older system, if you are seeing an upgrade alert.

But upgrading will not help you to order your calendar for printing from Apple, because Apple is no longer supporting print products since September 30. All last orders had to be placed by September 30. In Photos 4.0 you the tools to create an Apple-calendar or book project or cards have been removed completely.

If you upgrade to Mojave or High Sierra you can install third-party project extensions in Photos. The project extensions may be able to convert your project to a new format and you can order the project from a third-party Print service. But I am not sure, if this already working for Calendars, see:

See: Old Toad: Post 9/30/2018 Printing Options for Photos

Also these support documents:

Use Project Extensions to order print products in Photos after September 30, 2018

Create and order print products in Photos with Project Extension

See this article Use Photos on your Mac - Apple Support

• Update your Mac to the latest version of macOS.
• If you use iPhoto or Aperture to manage your photos and videos, upgrade to the Photos app.

Read this also How to upgrade to macOS Mojave - Apple Support