If the host not have had wwoofers with child/ren before it can be problems. And also if the host are not used with small children. A farm can be a dangerous place. Tractors, animals, machines, building material and so on. One has to be very carefully with the children so no accident will happen.
And only one child takes up much time. So check it up very, very carefully with the host so they do not have any doubts with a family with rwo small children. The host can not plan to use one person full time. Because sometimes it takes more time to take care of children than one person can do. And if that happens when it is very rushy it can be some collisions. The youngest mostly sleep and do not so much noise but the older needs to move around and discover the surrounding.
But of course it is fun to have children around.But it ill be that the host also will take care of the children. And you maybe have other rules for your child than the hosts have/had for their children or how they shall behave. Then there can be irritating.
So if you carefully ask and check up the host-conditions it will probably work.
We had a French woman with a five year old son some years ago. She went to Sweden just because we (at that time only Sweden had that law and culture) do not and not are allowed to spank or smash our children if they do not do as the parents say. I do not know how it is now. More countries do have same rules like Sweden but culture is strong.
To raise children is one of the most intimacy and deepest cultural act we have.