Can I blit a surface in an openGL context?

I am using Derelict3 which is is SDL2 and GL3 core. I have a deferred shading setup and am thinking that once I have drawn the screen aligned quad with the textures from the first shader pass I am looking at a SDL_Surface and am wondering if I can blit my hud straight onto the surface before calling SDL_GL_SwapWindow(win)? Or do I need to render texture mapped quads in front of the main screen aligned quad?