So sorry to read your post, Joe!
Your mother's doctor can, of course, give you the exact answers to your questions. However, it is extremely likely that they will suggest chemo in order to slow down the growth of the cancer and give her some more time with you.
Britain was the birthplace of the Hospice movement, and this is something that you should certainly explore when the time comes. Again, you mother's doctor is the only one who can tell you when this is. From my personal experience here in the US with several family members, I would say that Hospice is the best thing we could have done. So often people tend to wait until the very last minute to seek their help, and so miss out on so much that they offer. Hospice workers were the ones to help us figure out the answers to a lot of the questions you pose as to the "how long" and "what will happen" ones. They are also experts in pain control and are wonderful for making the last days count.
Wishing you all the best
Sara Anne
