I think your idea is great. Sailing schools will teach you things the right way before you learn bad habits. Especially, if you are ultimately planning on a larger boat in the future.
But as others have said, consider buying
yourself a smaller day/weekender type boat and get out as much as possible in the mean time.
To also repeat what the others have said, involve the family
in all aspects. If one family member
hates it, it could shatter the entire plan.
See if your sailing school
also does day hire. As you progress with your lessons, you may be able to take the family out with or without an instructor on board. Oh, and let "them" steer the boat and enjoy the fun.