I think it would be quite dark ahead. Apparantly the speed of light is the maximum velocity in our universe. So, if someone would be travelling with the speed of light, emerging light beaming ahead would mean, that the beamlight is travelling faster than the "normal" speed of light relative to other objects
Look at the light of the stars. Most of the positions between our earth and the stars are not fixed. Either because of the movement oif the earth around the sun, or the movement of our solar system in the Galaxy itself, or the movement of other star systems, or because of the spiraling movement of our Galaxy. Or better, take the movement of another Galaxy compared to our Galxaxy (expanding universe).
A star, which has a relative movement towards us, is emitting the light exactly at the same speed as a star, which has a relative movement away from us.
Why? Because the speed of light is fixed. It is the maximun possible speed. So, if an object would travel at light speed already, the light of the headlight wouldn't be able to accelarate away form that source.