Is a self-made parenting plan legally valid?

Questioner

I have drawn up a parenting plan together with my ex-partner, which states what we have agreed on regarding the children. We have neatly noted all our details and those of the children in this plan. The landlord of a housing association claims that a self-drafted contract is not legally valid. In my opinion, a properly drawn up contract with all the necessary details and signed by both parents is legally valid. My question is whether this is legally valid?

Lawyer

If you drew it up together, then it is valid. I understand that you were not married and did not have a registered partnership?