Hello Peter, and welcome.
For the dry mouth I found that whole milk worked quite well for eating. A product called Biotene mouthwash works as a thicker and longer lasting effect in the mouth between meals. I can't say if it is available in the UK but they have a web site
www.laclede.com They have a whole product line for dry mouth. As to getting any salivia back, it seems everbody is different. Some get none some get some. It takes time though, I got just enough back that I can talk and get through the day without the water bottle constantly by my side.
As to your other questions I can't help you. I didn't get chemo. There may be others that will.
Good that you have made it through the tough part!