It's not bad, it's more of a story set before An Unearthly Child rather than a prequel.
There are 11 books in this series one for each Doctor which all have one ongoing thread.
There isn't enough continuity to call it an arc.
No, you're thinking of Destiny Of The Doctors or the kids novellas, not sure which - this is Big Finish telling the story of the Doctor leaving Gallifrey.
Hah , I am 0 for 2 this morning, my brain is really mis-firing.