Chas, welcome to you!
OK, since you're new here I will tell you that I'm not a former JW, and not currently a Witness either--that is my Ex's religion, it has never been mine. So while I'm not an ex-Witness, after living with Witnesses for many years I do side with those who left the organization.
I would suggest reading the works of their founder, Charles Taze Russell, but there are problems with doing that.
First, they are hard to find, especially through loyal Watchtower channels as you requested. Ironically, your best source for early Watchtower teachings will be through "apostate" groups, such as freeminds.org.
Second, the Watchtower has replaced many of those teachings with different ones since then. In particular, many doctrinal changes occurred when Joseph F. Rutherford took over the organization following Russell's death.
So if you want to read all about Watchtower doctrines and don't want to learn them from "apostates", you will need to turn to third parties: perhaps the Knights of Columbus, an evangelical like Maurice Barnett, or the Institute for Religious Research.