I read the book last year and I was 20 then. But I don' think age a crucial factor in understanding it (well, if you;re more than let's say 16 or 18 and you have already devolped an ability of abstract thinking).
The book is written in such a way that laymen can grasp the ideas and the theory posed there. I didn't chceck a lot of words either, but as I wrote before now i check around 5 words per book, but I started reading in english when i was 15.
Returning to the content of the book itself, Lovelock is not trying to say that math contrains natural phenomena (it can't, math is just a language for describing abstract terms, physiscs is the study the desrcibes reality by means of mathematical formulas) The point is that Gaia is a self-regulating organism. the Earth is not treated as sepearate elements that have nothing to do with one another, but all the components contitute Gaia's body, in very much the same way as human body works.
All the species existing on our planet are opmpared to the cells and tissues that our body is bulit of, and all of them lay a crucial role. If some of them are overly abundant, it means that the netural balance is disturbed, so Gaia will make attempts at redressing the original harmony (homeostasis). It's in the same was as human body will try to combat the too big number of white blood cells (leucocytes), when we catch a cold.