My ds has a new girl in his class, maybe she's yours........ Our school is quite small and I struggled during the whole of last year to convince myself that both he, and I, would fit in. The school has a good Ofsted, the staff are lovely, but a lot of the parents looked/seemed very "couldn't care less" shall we say.
Fast forward a year, my ds had a fab year, his classmates are lovely and he did so well. The other parents are lovely, even if some of them are a bit scary, and generally, I wouldn't change his school for anything, I'm glad he didn't get any of his choices and ended up there. He ran out of school today saying that Y1 was the best year in the school etc etc, he is so glad to be back there.
As long as a school gives every child the opportunity to reach their full potential, then even the less academically inclined will blossom and behave, just because they enjoy school so much. I would say that in his class of 23, maybe about another 2 are on his level academically (he's bright, but not a genius), but they are lovely, lovely, children, it just took me a while to figure it out.
So, although I do understand your reservations, give it a chance !! (and note, I am a "professional parent" but often turn up at the school gets with child snot on my shoulder/in my trackies/letting my 2 year old eat a lolly at 8:45 in the morning..........)