I have the SuperPlus 16 sample test book from Etrasa. I just took the test this May however I also signed up at a driving school as I could use their computers and do their sample tests which was the most help and the cost difference to study on my own or sign up with a school was marginal.
You can also do sample english tests directly from the trafico website: http://aplch.dgt.es/aeDGTWeb/examen/TiposExamenes.htm
I probably took over 250 tests and took each one until I got everything correct (or only one wrong) and I still found questions on the exam that I hadn’t seen before. Unfortunately I failed the first exam as I got 4 wrong but passed the second.
The practical test was another fun story.
Let me know if you have questions on anything!