Turn up on the evening, pay your 12 quid, and you can get the photo, with Co-op Membership thrown in.
It's really that simple.
You can even use your phone and sign up and pay online during the game.
I think you'd have to be a real anti-co-op person to reach the cutting-off-your-nose-to-spite-your-face stance of refusing to go despite wanting a photo taken because you refuse to be a member.
About the only pre-requisite of membership is you have to Not be wilfully against/working against the core aims and ethos of the organisation. And given what those are (ie. Communication with the Club, representing fans rights, monitoring and safeguarding the Club, readiness in an emergency/phoenix situation) I can't see too many County fans being in opposition.
You don't have to vote, volunteer, join in, go to events, stand for or be on the board (although the more that do, the merrier!) If you don't want to.
We've made it abundantly clear in all publicity that you can join up on the night if you're not already a member.