"Lougle, I like the way you always need me to prove myself. Its helpful because Ive spent the weekend thinking about this. "
I hope that you don't perceive it as it sounds, because you don't have to prove yourself to anyone, least of all an internet-stranger 
But it isn't helpful, in my experience, for people to just pat a poster's head and say 'there there it's terrible, aren't they meanies?'.
To get the system to work with you, you have to know the system, and know what it is you want the system to do, and why.
Re. the hip injury - did you ask the pre-school why he had a hip injury? If you didn't, that's the very first place to start. Each and every time he comes home with any injury, you need to contact them as soon as possible, and say 'x has this mark, do you know what happened?' You should be being asked to fill in the accident book, and if you aren't, you'll have to ask that they make a record of it in there.
I think, if it were me, that I would take the following view. Please bear in mind, that I am no expert, I am not saying this is the right approach, it is just one option:
I would first go in and informally raise concern. If they say they don't feel there is a demonstrated need for 1:1 at this time, don't get upset. Leave the conversation. It will get you nowhere to push the point, and just make you look neurotic.
Then, I would write to the pre-school, outlining your recollection of the conversation. I would also refer to any documented evidence you have, and include a copy. State very clearly that you are concerned on Health and Safety grounds for the wellbeing of both your child and other children. Ask that a copy of your letter is filed in your DS's file. Copy it to the local Inclusion Service (or whatever they call it in your area).
See where that gets you.