Once you have published your dissertation as required, you will be issued your doctoral certificate at the doctoral awards ceremony. If the publication has been delayed, you will receive a provisional certificate at the awards ceremony. In this case or if you are not able to visit the doctoral awards ceremony, your doctoral certificate can be retrieved at the Dean's office personally or with a written authority.
Since the certificate is a sealed document it cannot be send via post.
The dates for upcoming doctoral awards ceremonies can be found here.