Panda, I think you have done a marvelous job this past 2 years.... taking care of your kids EVERYDAY. You are indeed a super mom!!
Welcome back to the working world. one thing though... Work will never be the same as it use to be before kids. You will need to be able to compartmentalize work and home... sometimes at home, we worry about the kids... and sometimes at home, we might be worrying about work we haven't completed. but really need to learn to compartmentalize and shut off automatically when you move from one mode to the other.
The good news like Gan said is you have your free time at lunch and also the quiet time to yourself at work. This time is extremely important for you to connect with yourself again, and take time out to relax and enjoy your me time. Cuz the minute you reach home its back to mommy mode!
On the downside, the sleepless nights suck, especially when you have to drag yourself up the next day, put on your game face and face the world at work. And when kids are sick, thats when it gets hard to juggle both. There is also the guilt you will feel from time to time for not spending enough time with them. But on the bright side, the weekends are great... you feel energised to spend time with them cuz you miss them so much during the week!
You will do fine!! Good luck!