Prelims in other games where Collingwood or Essendon are involved would be difficult for you.
You have a great option to attend the couple of games you want, prelim though may be a hard one, all depends if we make it and who we are playing on the day.
With a country membership you have to wait until the Wednesday to buy a ticket, as you are not a member who is eligible for the members sale (Monday).
Maybe, would look at getting a September membership also, may cost more, but will get you into all finals even the GF.