I just saw it. It was interesting but they jumped through a lot of hoops.
The Plan should have just been:
-To breed human/Cylon hybrid babies, born of 'love'
Back in the 1st season I actually thought that's what it would be all about... Helo/not-yet-Athena... Boomer/Tyrol... Baltar/Six.... all human/Cylon pairings in which they attempt to create 'love', then a hybrid child. It seemed to fit.
It's implied that that was a sort of sub-project lead by the Fours and Sixes primarily. Cavil attribues the farm as being run by "you Fours", and we get some insight into Simon's struggle with love in the fleet. One thing that is clear is that the Cylons were never all completely on the same page, and while Cavil was organizing the attacks, he wasn't their leader per se, since everything was done by vote. So the grand plan was a simple one... annihilate humanity. Beginning at that moment or even before perhaps, individual Cylons were hatching their own plans... D'Anna and "her own path" as Cavil put it, Simon and his farms, Six and her experiments with love, Leoben with his Kara/God/Destiny freakshow, and as time went on they diverged till we know how that ended in season 4.