Welsh Government has revised the guidance and it states:
Every child who can be safely cared for at home should be and only where there is no safe alternative should provision be made in schools or other settings.
If you are classed as a critical worker but are able to perform the critical parts of your job effectively when working from home, then you should do so.
If one parent is a critical worker but the other parent is not then the other parent should provide safe alternative arrangements at home when possible.