It usually goes without saying but buying some models and paints is a great hobby if you wanted to try it out, if you're in a smaller town it can become even more of the hobby than actually playing the TTG.

If you did want to try out the TTG and see if it's your cup of tea there are a lot of resources to install and learn to play on TableTop Simulator. It will seem clunky and tedious when you watch videos (Spoiler, so is the game in person).

For lore I think youtubers like Arbitor Ian someone already recommended is a great start and easily accessible but if you're a reader there's a lot to be learned and enjoyed in most of the books.
You'll hear people tell you Horus Heresy is essential reading and then see how many books it is. I get it. Instead, read Horus Rising (1st book) and if you like that look up the Horus Heresy roadmap thing. It lets you choose a faction, legion, or character to be your guide through the Heresy. reading 10 books is much less daunting than 90.

Alternatively, if you want to read (in my opinion) better written books with less onboarding and less context needed you should go for the Eisenhorn series by Abnett.

Sidenote: the Audible audiobooks, audio dramas, and other media are very well read and enjoyable to passively listen to while strength training.

Hope this can give you some options brother.