”Today is a holiday instead of working of tomorrow.”

   Do you want to say you do not work today, or do not work tomorrow? You can say: "Today I don't have to work." "Today is a day off work."  

"Sometimes, i have to go to work on Saturday or Sunday because i work in the hospital. The Hospital never sleeps all day."

    "Sometimes, I have to go to work on Saturday or Sunday. I work at a hospital, and the hospital never sleeps."

"I am going to go to the bed early for tomorrow."

    You can also say, "going to bed" instead of "going to go to bed." I think this sentence needs an explanation: "I'm going to bed early because..." For example: "because I have to work tomorrow."

In American English, we say we have a "day off" work. We only say "holiday" if it is an official holiday, like New Year's or Thanksgiving. In British English, I think they say "holiday" (but I'm not sure).

よくできました！