Name change BRP advice

[Twogan45]

Me (British) and my wife (Australian) married in July 2020 and she received her first FLR(M) in October 2020.

She now wants to change to her married name. Her current Australian passport expires in October 2021, so we want to renew in September 2021, and get the new passport issued in her married name. However, the Australian Embassy in London aren't taking passport appointments at the moment due to COVID-19.

I understand that, when you change your name, you must request a new BRP from the Home Office to be issued with the new name.

When requesting a new BRP, what documentation do we need to provide? I'm guessing the new passport and marriage certificate? Is there anything else, e.g. copies of bank statements/utilities showing the new name? Or should we wait until after getting the BRP before changing her name with the bank/utilities/phone provider etc.?

Will we have to physically send the old BRP when requesting a new one? Processing times could take months and my wife is starting a new job in September so doesn't want to be without one for long.

Will the old BRP be valid against her new passport, whilst we wait for new BRP to be issued?

Many thanks for your help.