Courtesy of reader Silver Elixir, here's another potential source of family-planner forms.
On The Organized Mom section of Parenting Weekly, there are links to lots of different household forms like Babysitter Instructions, School Shopping, and even Parent Activist (for tracking political contacts).
The forms are Web pages (HTML), and there's no Print button. But I've found that you can carefully drag the mouse over the form to select the entire table, and then paste that into a word processing program. Then you can print onto whatever size Filofax paper you wish from your word processing program.
Here's a link to Silver Elixir's own custom-made tabs:
This link is to one photo. Keep clicking, because she has created lots of tab options, including some top tabs she printed herself!