I liken it to this scenario, if you were overweight and wanted to get into shape, would you only exercise and diet every second week, or "here or there" and expect satisfying results??
Similarly, taking up an instrument requires some commitment and dedication. If you are considering taking up an instrument but are not willing to commit to a lesson time every week, I certainly would not accept you as a student, no matter how big or small your goals are. Although I can not read the future, I can guarantee that if that is your mindset, you are most likely not going to get the results you are looking for!