I 2nd that - don't do a private agreement. My DH works at CSA, so if you have any questions, PM me and i'll get him to respond. Otherwise look up the website, there is a lot of info on there.

I would call them, and speak to the new clients section. Get them to explain everything, how CS works, how the calculate it, how it affects you (and yes, DH did say that the amount of CS you receive does affect your FTB, but there is a maintence threshold that applies before you start getting deductions). Also, ask them about cases of DV. It means that you will still get full FTB, but then you won't get any child support at all.

And yes, every parent in this country has a legal obligation to support their children.

Even if you just call up and get some info on the phone, and sent out to you, you can start the process slowly.