I'm wondering if I should read/work through at least the first bits sometime: it's well over a decade since I did any maths and it might be good for my brain to have the refresher.

I'd say give Chapters 1-5 a try first, see how you get on. The difficulty ramps up slowly and the concepts stay pretty grounded in 'reality'.

Chapter 6 seems to be the point where things get 'messy', suddenly you are into 4D space, polar/spherical coordinate maths, multi-dimensional complex numbers...

... for me as a maths geek first and an engineering/science geek second (the distinction being that maths is a tool for the latter, and an end in itself for the former), its at this point that I become utterly bewildered by the fact that some of these crazy, esoteric concepts have any use in reality whatsoever

And then my head explodes and I go and have a cup of tea.