I personally do not like GL: Secret Origin that much. Writing character based stories is NOT Geoff Johns' forte imo. Give him sprawling space sagas with lots of characters and archetypal characterizations and that's more his game.
I do however envy you - you might have some really good stuff coming up in your future. I would strongly recommend picking up all GL comics from GL: Rebirth and read both GL and GLC comics all the way thru end of Blackest Night.
Here's an amazon checklist
which lists all the collected trades and may help you find the comics in Comixology. (Haven't really used comixology - I prefer the physical comics. Trades from the friendly neighborhood library are best!!)