This is my lovely guide to Classic Who and the extended universe:
The episodes: download | online (and how to navigate the site) | The TV Movie (the Eight’s only televised story until “Night of the Doctor”
Webcasts and Other Specials: Dimensions in Time | The Five(ish) Doctors | Scream of the Shalka 1 2 3 4 5 6 | Shada | Real Time | Death Comes to Time 1 2 3 4 5 | Curse of the Fatal Death | The Infinite Quest
Some novelisations and stories: Engines of War | Target Novelisations | Lungbarrow | Bernice Summerfield | Feast of the Stone
A good deal of audios (but please try to buy these whenever you can via Big Finish; they need and deserve the money, they frequently have sales on full stories, and a lot of their older main range stories are only a couple dollars each)
There are a lot of torrents for the comics or the other novelisations that can be found via a quick google search, but these are all the links I have for direct downloads and pdfs.
Finally, be sure to check out some of the other classic who blogs in the classic who tag and on the Classic Who Directory, too, it’s a nice community with some very knowledgable people. Don’t be intimidated, no one has read every novelisation and comic, listened to every audio, and watched every story, but between all of us we’ve got a good deal of the Whoniverse covered
(ps if anyone’s wondering why the ask is so awkward I sent this message to myself from my friend’s account to remind myself to send this to her and I’m bad at talking)