I live opposite a school and every school day parents will park their cars over our drive, so we can’t get in and out (we have children also and my wife is on mat leave). What can I do to get them to stop?

Apparently the school can’t do anything about it and some of them are incredibly brazen about it.

What can I do that won’t get me in trouble with the police/baring in mind they have children with them? Any other means are fine.