Documents needed for visa to visit daughter in China

Invitation letter from your daughter is required, and copies of her passport, work Z and residence permit. Proof of relationship should be provided, so, her birth certificate and your marriage certificate as well. Basic requirements are your original passport, application form, photo and return ticket.
As I know, the embassy does not provide mail back service. It can be collected in person or through someone entrusted with pickup form.

Many thanks for that excellent reply. Just one more question ( I think, though probably more will occur to me! ) - will a copy of my daughter's birth certificate be sufficient!

No, as to my experience, both photocopy and original of the birth/marriage certificates are required.