Dave Filoni's series has always been a hot topic of debate among EU fans. Most would do away with it altogether while others (myself included) grudgingly accept it into the canon as Lucasfilm intended.
Rife with contradictions the show did have some good ideas from time to time and deserves more love than it gets.
The following episodes will be directly addressed in the novel:
Season 3: Episodes 12, 15-17
Season 4: Episode 5
Season 6: Episodes 11-13
Breaking them down for you a little more, S3 E12 is titled "Nightsisters" and was the one where Dooku went to kill Ventress a the request of Sidious. While E15-17 is the infamous "Mortis" storyline that was drawn out in the Fate of the Jedi series.
I can only speculate if this means if Abeloth makes an appearance or we get more of her background. I'll be interested to read about it whichever it is between the two.
S4 E5 "Mercy Mission" is a droids story featuring 3PO and R2. I honestly don't remember much about the episode but do plan to watch it again prior to reading the book.
S6 E11-13 is part of the "Lost Missions" series and features a Yoda story arc. This is another one I don't remember that much of because I only saw those episodes once. But again I'll watch them prior to the novels release.
There's nothing about Season 7 being mentioned in the book to which I'm relived since it takes place completely in the new canon era.
Thank goodness for the little things.