SANDS Head Office will have some advice for you - the hospital should put your friend in touch with them anyway.
As goingfor3 says, because the baby was over 24 weeks when he/she died, both birth and death have to be registered
With regards to the funeral, thanks to a campaign by SANDS some years ago, many undertakers will provide a simple funeral service in these circumstances, free of charge. Crematoria will often waive their fees too. Your friends can choose what, if any, type of funeral to have for their baby.
Hopefully the hospital will have a bereavement midwife on the staff, whose job it will be to liaise with your friends, maybe even be present during labour and delivery, and to help them through the procedures such as the post-mortem and follow-up care at the hospital.
As I understand it, your friends are not required to have a post-mortem if they really don't want one done. It may well be able to tell them why their baby died, and it is recommended. But in about 50% of stillbirths overall, no reason is found, sadly. However, it can also be used to specifically rule out some causes of stillbirth. We had one, and despite no cause being found, and the delay it caused in being able to say goodbye to Tom, I feel it was the right decision.
You sound like a great friend . It is very tempting to give people whose baby has died a wide berth, for fear of intruding, or saying the wrong thing, whereas in fact you can feel totally alone and shunned in the days after such a shattering piece of news. Cooking, childcare, they're all helpful and welcome, but the chance to talk about their baby (by name if they choose to name him/her) and grieve with someone who's not afraid to be there, is the best thing you can give your friends.
We lost Tom at only 21 weeks but he was a desperately wanted and long-awaited second baby (five years ago this month). My heartfelt sympathies to your poor friends, and to you too, I know this sort of bereavement has a huge impact on friends as well. XXX