Sorry I haven't read the full thread as I am rushing to answer. I'm glad you have Marie Curie and Macmillan involved.
It sounds as though your Nan is close to the end now. She doesn't need food, but when she stops drinking do try to keep her mouth moistened with water, eg on a soft clean cloth. When she wakes up, you could see if she wants some sips of tea or water, but don't try giving her fluids while she's unconscious.
Are you getting professional carers in to help with her intimate care?
When I was looking after a relative in similar circumstances, I was astonished to discover I could not lift her, once she had become unable to lift herself, even though I was quite fit and she was much smaller than me. Even with another relative helping, we could barely move her, and our efforts were hurting her as she had become very fragile. We needed to wash her, change her pads and (as the disease progressed and she was mainly unconscious) turn her from one side to the other to try and stop her getting bed sores.
I contacted the local hospice and they sent in two carers at a time, three times a day. They were trained professionals who could do it all without disturbing her. This, and all the other help the hospice gave, was free of charge. If that's not available where you are, you can hire carers privately through care companies.
I wasted time at the beginning by trying to find out how to get help. Surprisingly, her GP didn't give much information. I found the district nurses and the hospice were the most helpful, in providing both services and information.
I learnt to write everything down that I was told, because it's very easy to ferget things and get muddled when you're under such stress.
When my relative wasn't waking enough to take medication, near the end, the district nurses came and gave her injections.
Also, make sure you and your Mum are looking after yourselves too, eating healthily, drinking enough and taking turns to go out for some fresh air every day. I've done a lot of manual work during my life, but I've never been so exhausted as when looking after someone who was basically not moving and not making any demands. The emotional strain and the responsibility can be overwhelming.
I felt wiped out for weeks after she died. It was like recovering from flu. But I was so glad I had done it.
You're doing something wonderful and repaying your Nan for all she's done for you, helping her die peacefully in her own home. I hope everything continues to go well xx