Free diary inserts to download
https://philofaxy.blogspot.com/p/diary-inserts.html
They're available in A4/A5 and Filofax page sizes and in various layouts.
I do this every year and print them out as double sided booklet mode on a laser printer, then I put them in an A5 ring binder.
It costs a few pence to print and is a lot cheaper than buying a printed diary.
The website also has loads of other downloadable organiser style pages.