If we were to dimatirialize our bodys and convert it to energy, could we move almost as fast as light in space

i dont think we would want to, because as we move, our light energy bodies would redshift, becoming longer in wavelength, ultimately, we would cease to exist ^_^

As a quanta of pure energy, the tendency is to dissipate into the background, unless acted upon by an external source. If you meant will the dissipation spread at near light speed? Yes. But that doesn't mean you will travel to any place at all. Your embodiment (the entangled part of you with the surroundings) spreads out, but you don't travel.

If all of the elements and compounds in your body mass could be converted to light energy, "you" would indeed move at the speed of light - unfortunately, this would be a one way trip.