Varsity Football? Im a freshman?

Ok well i am on the freshman football team. I am an offensive lineman and i weigh 173 punds. I just had my last game of the season and we won. After the game, the coaches called me over and asked me to practice with the varsity team for the remainer of the season, which is 2 full padded practices and a game. Now, im pretty good at line, p protection is my strength, not so much run blocking. I have a feeling i will get crushed at practice. So some questions: Do you think the coaches will be as hard and tough as me as all the other players, even if i like have to tackle a senior or something? What are some ways to make me be less scared of practicing with them, because honestly im scared shitless. Any advice would be helpful