Graham - I totally get what you're saying. It's hard to take advice from someone who has no first hand knowledge of what you're going through. I found a couple of links that I hope will be helpful to you.
This first link is to a form you fill out as a caregiver and they match you up with someone who is dealing with the same thing - same cancer, same treatment, etc.
http://www.cancare.org/look-for-support.asp
This second link takes you to a page with links with information for caregivers.
http://www.cancer.org/treatment/caregivers/index
Good luck.