There are plenty websites that supply music for these instruments, so you may be certain that you can obtain practice scores. Copyright law allows you to acquire such items from sources that have the right to sell them and to keep a copy of the score on your laptop, either in printed form or electronically.
The free download variations are at the legal limit, since they fall into the same category as movies and videos, which circulate in the virtual world without any control over their origin or usage.
We would like to emphasize, however, that once acquired, such a score may be used just for personal use, school, or performance in front of family or friends. Once your representations become public or serve as a source of revenue in any way, you fall under a different set of rights that are not often associated with items sold online.