Hello mummy2018
I'm very sorry to hear about your mother's diagnosis and the heartache you are going through at this time.
I recently joined a webinar called 'How to talk to children about death' that was led by wonderful Poppy's Funerals in Wandsworth
https://www.poppysfunerals.co.uk/
I know that they recorded it and I'm certain they will send it to you if you contact them. They are the most wonderful team of ethical funeral directors and will help you in every way as you prepare to talk to your children (irrespective of your choice of funeral director).
I was lucky enough to meet Poppy at a local community event where she was talking about her mission to be a resource and support for people experiencing death. There are many features on the website to share information and help you navigate your way forward for yourself and your children.
I unexpectedly had to arrange a funeral after meeting Poppy and I decided to try out her service - it was absolutely flawless and delivered with such compassion as well as transparency (how my deceased relative would be cared for / funeral options & costs etc)
With my warm wishes and best thoughts,
sunnyjan