In this paper we introduce a semiclassical simulation model that address the above issues at the cost of other significant approximations whose effect need to be carefully addressed as well. In this model, the molecules are represented, as in the TC model, by two electronic state and (in the present implementation) one nuclear mode. The assumption that the nuclear motion is harmonic is relaxed, so reactive potential suraces may be considered and in the implementation described below the upper potential surface is taken to be repulsive. The cavity is described as a metalic structure of any desired shape where the metal is described by its dielectric response function, and is taken here to comprise two parallel metal plates of a given thickness with the molecules distributed in the space between them. Solving the corresponding Maxwell-Schrödinger equation for this system yields the full scattering dynamics and in particular the transmission and reflection signals obtained in response to an incident light. The frequency dependence of these signals reflects the consquences of light-molecule coupling in the presence of the metal interfaces and, as shown below, account well for the polaritonic nature of the calculated optical respnse. At the same time, the reactive dynamics following molecular exitation can be numerically monitored and its behavior in and out of the cavity can be characterized.