Removable partial denture or complete denture will cost much less, unless she insists fixed restoation, which may require ridge augmentation to accomodate implant.
At the very least, she should get a second opinion or even a third.
I can't believe that there aren't other alternatives, and cheaper ones! I have severe bone loss on my bottom front teeth, and have been told by dentists that they don't know what are holding in the 2 teeth. 32 years ago I was told that I would lose these tooth teeth within months, and that I needed to do something about them. I did nothing and still have the teeth today, 32 years later!
I guess they do things differently in England. Take bone from the hip. Kind of expensive for only upper. I have one advice, i am sure they are going to do implants for her, she has to make sure she is not having osteoporosys, if she does, her bone transplant, and implants are going to fail. Especialy, if she lost bone around her teeth, because of osteoporosys. She has to get a bone density test first, before anything is done in the mouth.