I would also suggest to forget about Hull and Wilmott and would suggest to start with the excellent book by Shreve: "Stochastic Calculus for Finance. Volume II: Continuous Time Models".
Then, you can quickly read Bjoerk, work through Brigo/Mercurio (if you like that style) or Andersen/Piterbarg. Alternatively, if you want to fully dive into into the subject after Shreve, Musiela/Rutkowski: "Martingale Methods in Financial Modelling" is wonderful.
Then, you can quickly read Bjoerk, work through Brigo/Mercurio (if you like that style) or Andersen/Piterbarg. Alternatively, if you want to fully dive into into the subject after Shreve, Musiela/Rutkowski: "Martingale Methods in Financial Modelling" is wonderful.