I am looking for introductory texts on Ehresmann connections and Chern-Simons forms. I seek detailed, hands-on presentation. Please, recommend sources that employ a differential forms approach rather then the algebro-topological one. Of course, the latter is also welcome.
Let me state my background. My understanding of homological group theory and algebraic topology is poor. I have basic knowledge of differential forms and differential topology. I am vaguely familiar with characteristic classes and invariant polynomials.