Regarding the lore would I recommend the podcast Adeptus Ridiculous. It is great for newcomers and you will fast get a grip of the overarching themes, stories and what not. Then just pick up a book on the story that you find the best!

For the table top I’d say, unless you want to start directly, look around for the theme of an army that you like the most. And when you have decided on an army buy their combat patrol box. Whatever you do, however, do not just buy what is good or meta right now as that will probably have changed by the time you have finished painting your box. Rules are temporary but looks are forever!

If you want another podcast tips on the hobby and table top side would I recommend the poorhammer podcast. Especially episode 66 which is made for newcomers to the hobby.

Have fun and welcome!