what I seem to be missing is something on how to fly the different instrument approaches
Unfortunately much of instrument flying is a practical skill. It would be a bit like trying to learn to play a musical instrument from a book alone.
The books will give you the technical understanding and limitations of each of the aids, but nothing can replace practical instruction. Even MS Flight Sim is an invaluable tool to see how things fit together, the rate of closure of a bearing/localiser etc. Also try the RANT simulator.
Much also depends on which licence you are planning to add the IR to. I am currently reading the FAA ASA Test Prep book to add my IR to my US licence. It's completely different from the CAA ticket.