Heya, anyone can partake, and there is still plenty of time for non-CoG'ers to get to requisite level in game.
To take part in Clash of Gods you have to be level 30. If you follow this guide
you can get to level 20 in about an hour or so, as for the remaining 10 levels, these are quick to complete since the devs recently updated the game to speed up the early levelling process and takes probably a day to do, so even if you levelled at a leisurely pace you will certainly get there in the 11 days left for getting the badge.
Once you are level 30, click on this icon
at the top right of your game screen and select either holy or dark side or destiny (random assignment) from the options given (if you chose destiny you get a gift box, but please note which side it assigns you to).
Once you have done that you are all set to go.
The Clashes have set times, Monday, Wednesday and Saturday they are held at 8pm PST and Tuesday, Thursday, Friday they are held at 2pm PST. Server 7 clashes last for 3 hours, so this server will probably be the most convenient and flexible time-wise for you.
Turn up, enter the battle field through the same blue star and then by clicking
You do not need to kill the boss to get the badge, just show that you took part in a fight. During the fight, your whole league will be participating at the same time. So getting the badge isn't that hard at all.
If you have any questions, I do not play s7 but I watch that server under the name of Phoenix if you want to speak to me in world chat, otherwise Sav or I are usually about in sb if we are online.