What should I read before tackling Michael Huth's Logic in Computer Science: Modelling and Reasoning about Systems?
From the Preface of the 2nd Edition:


  The book requires that students know the basics of elementary
  arithmetic and naive set theoretic concepts and notation. The core
  material of Chapter 1 (everything except Sections 1.4.3 to 1.6.2) is
  essential for all of the chapters that follow. Other than that, only
  Chapter 6 depends on Chapter 3 and a basic understanding of the static
  scoping rules covered in Chapter 2 – although one may easily cover
  Sections 6.1 and 6.2 without having done Chapter 3 at all.


Of course, having elementary prerequisites and being easy are two different things. I've only read the first two chapters as a way to self-teach some logic so I can't comment on the 'latter' material. 

The cool thing is that you're only obligated to read the first chapter and then you can proceed to read most of the other chapters in whichever order suits you. If you want a free supporting material, there's the Stanford Logic MOOC and the Mathematics for Computer Science course from MIT.