Your info on child benefit says:
On 6 April 2017, the Government’s“two-child limit”came into effect. This means that, if you already claim child benefit for two children, you cannot claim for any further children you have. If all your children were born on or before 6 April 2017, however, you can continue to claim child benefit for them all.
This is incorrect as child benefit is not subject to the two child limit. In fact the .gov website says this:
You get Child Benefit if you’re responsible for one or more children under 16 (or under 20 if they stay in approvededucation or training). There’s no limit to how many children you can claim for
The two child limit applies to Universal credit/tax credits, etc but not child benefit