Depending on how much time you have there are two main ways:
1. Have 30 min call with parents and ask them specific questions plus any follow-up questions. [ You will get fewer responses but might get other extra useful information ]
2. Create a detailed survey with questions you would like to get answered. [ You will get more responses to the questions you ask ]

You should try to get a list of parents from your network ( on social media, previous school groups, previous work mates.

There are other options which will require a budget. Happy to answer more questions on a call after understanding your business better.