Hi Experts!
I'm a home reno novice. I've removed paint, sanded and repainted a side board.
I'd really like to build floating shelves for books above my desk in my home office.
Something like this only longer and in a natural oak timber colour: 
It's a 4m long wall. So I'm hoping to have at least a 3m long shelf, 40cm deep. It's to be mounted against a blockwork wall (middle apartment) so I should be able to secure something pretty strong.
I'd like it made from a decent piece of timber - I wanted live edge but that's getting a bit out of my price range, so now I'm thinking pine or tasman oak timber. I'm going to look on the weekend for reclaimed timber if I can find a piece long enough but they probably will be shorter.
How do I support this shelf? Is it with those chemset bolts? With the angle brackets? How do I work out how many I need, required spacing and how much loading capacity it will hold? The wood itself is going to be heavy, and then loading it with books will be heavier again. I don't want it to warp/sag/cause injury.
Is it possible to do it with two smaller pieces of timber? How would I do this?
Many thanks
Mags