The undergrad course is called intro the applied math, and it covers: "The unit introduces some of the principal mathematical techniques such as difference equations, differential equations and partial differential equations."
We are not given a textbook and I really want to study from one, the closer it matches to the course the better. I think it's definitely based on a textbook out there.
We are about halfway through the course. Here are some course pdfs https://www.dropbox.com/sh/u3ek0rjs7jczbhj/AAC86lV0wep07b-cua3dz00Oa?dl=0. BonusQ.pdf gives a good overview of the content
You could try these books: - An Introduction to Ordinary Differential Equations by James C Robinson - Differential Equations by Richard Bronson and Gabriel Costa
These are the books I used to use and they are pretty good, and your course, from your description, looks a lot like my first year differential equations course (I tried looking at your dropbox folder however for some reasons it couldn't load).
My lecturer's lecture notes are also very helpful, perhaps yours are too?
But yeah just a suggestion.