This paper considers the guidance and control problem of a flight vehicle with a seeker installed on the side of its head for avoiding the aerodynamic heating. In order to guarantee the target remaining in the seeker's sight of view, the line of sight and the attitude of the flight vehicle should be under some constraints which cause coupling between the guidance and the attitude control. Therefore, the integrated guidance and control (IGC) is necessary. We first formulate the guidance and control problem of the interceptor into an IGC problem with constraints. Then, a singular perturbation-based design approach is proposed to decompose the IGC problem into the control design of the quasi-steady-state subsystem and the boundary-layer subsystem individually. The receding horizon control is applied in the control design for the two subsystems. Simulation results show the effectiveness of the proposed approach.