Just have a fire extinguisher handy. I've painted my board with white housepaint, and even with the welding spatter thast happens, the only fire i've had is when i accidently left some masking tape on the table under where i was welding. I wondered why the tasck weld i just did was smoking so much.
A bit of burnt on the build table wont be that bad. Looks like you have been busy at the end of the day.