my .02
Hi Dark Sky, I've never read a single book or guide other than what I've read here on BHW and other popular IM blogs, but for the most part this forum has taught me everything I know. I'm not an expert writer by any means, but I manage to craft decent content for my own website. You're from the UK and I've been living the US now for over 10 years, I am 100% sure that you do not need to read a book to write meaningful content.
I think the biggest thing right now is Search Intent. I'll give you an example that I came up with once I started outsourcing a few articles that I did not want to write myself. I told my writers to not worry about keywords or anything else. Those can be sprinkled in later. What I told them was, imagine that a person is locked in a room. They only have 5 minutes to escape until the room gets filled with water. The only thing they have access to is your article. Your writing must reveal to them the exact method of making a clean escape. If you fail to do so, the person is going to lose their life.
When someone enters in a search query, that's the answer they're looking for. Put yourself in the shoes of the person writing the query, and then start writing. It is all that matters!