For the PSAT/NMSQT®, you can practice right here! The PSAT/NMSQT® has the same content as the SAT, minus the hardest questions and the essay. You can also download a PSAT/NMSQT® practice exam to take on paper.
The PSAT 8/9 has the same structure as well but with even more hard SAT content removed. Official Practice for the SAT may contain too much of the harder content to be really useful for you, but you are welcome to try out practicing with us.