I have never seen anything like this. No wonder I have been warned that I will feel sad filling it in, it's so bloody depressing. I suppose it has to be but the style is completely counter-intuitive, I mean - in a work situation you wouldn't dream of writing something so blunt and totally negative about another human being!
I'm already stuck, too. DS is only two, will he even have an NI number or do I put down the Child Benefit one? As that's the same as my DD's AFAIK...
Kudos to everyone who has ever had to do one of these