Should I be nervous about being a witness in Court?

Hi and hope you're having a good day. I've just recieved a letter stating that I may have to appear in court as a witness. In March of this year,a driver overtook mine and several other cars on a bend in a country road. Several minutes later,i saw his car and a man,dead in front of it. Something I'll remember forever. I gave a statement about the way this guy was driving. And now that i may be called in as a witness scares me. It's been so long. The case wont be in the Crown Court until possiblx early next year.What if i'm grilled down to the last detail? Will they pick me apart? Find fault with me and my statement? Or are English courts less harsh than the American ones portrayed on the telly? I do have a witness support person but i'd just like to see what you have to say first to calm my nerves. :-( xx Sarah