Good for you! Hal Higden's plan is a great one to follow. I started running a year and a half ago.. I've done several 5K, 10Ks, and HMs. I signed up and raced my 1st MARATHON this past January and followed Hal's novice 2 with the 1 20-miler. I was nursing a calf injury, so I wasn't quite as fast as I wanted to be.
Anyway, enjoy it! At the race, I tried to remember all the training was over, that I was prepared for the race, to trust the training. I took some of the gel packs with me and used them at mile 9,16,20, and 23. This really helped keep me from hitting the wall. I also tried to go a bit slower in the first half of the race and stayed with some pacers. The last 6.2 miles can be easily done!! These were nothing but a countdown to the finish for me. Every mile was one mile closer to the goal of running 26.2 miles at one time. Something I never imagined myself doing. (When I started, I couldn't run a half mile).
BTW, sounds like we have similar stories... I've had two boys (I'm 30 now), and started running to lose the baby fat/get in shaper.
Follow Hal's tapering at the end and resist the urge to do more running. This is important as it will refuel and prepare your body for the race! You'll feel like you have a lot of energy towards the lead up to the race (I did), so save it for race day! Happy running.