I’ve read in Ricki Carroll’s book (which is fantastic) that you can use calcium chloride to counteract the effects of the homogenisation process but can you tell me how much to use and when to add it please?

In fact, calcium chloride only helps, it can’t reform damaged casein micelles. Don’t use homogenised milk, but if you can’t get non-homogenised milk (a milkman often can deliver), then buy skimmed milk and double cream, and combine to a ratio of 12 parts skimmed milk to 1 part double cream. This makes a much better cheese than using calcium chloride.