Star, I totally get where you are coming from with this. My dd started last Monday and I feel exactly the same. Her life to date has been overshadowed by ds1's assessment, school issues and statement battle.
I can't believe the time has gone and she's off to school. I spent too much time researching stuff on the net, proof-reading documents, pushing doctors and psychologists, attending meetings and calling helplines and not enough time having tea-parties, baking, playing with play-dough and having walks in the park with her. 
She was desperate to go too. Talked about nothing else for weeks, spent hours parading around in her uniform at home, playing schools and then charged straight in there with neary a glance backwards from the first day onwards. 
I was so tempted to keep her with me until Reception, but I knew it wasn't fair on her, because she really wanted to go and I know how valuable it is for her to mix with nt friends, as her relationship with ds1 is tough going these days and ds2 is great with her, but learned a lot of his social skills from ds1.
Lougle is right though, by getting all that done for ds1 now, I can help her navigate the early years of school with as much attention as I did her brothers. I will be able to go to every event and special assembly, accompany school trips, help out in class and generally be far more involved that I could have been had ds1 still be struggling the way he was.
Mind you, she was off sick on Friday (first week of school and she came down with a stinking cold) and it was lovely to be able to cuddle up on the sofa with her and watch her favourite film.