This is interesting DrTinkle - my DGD is at a small all girls independent day school (only about 400 girls in the school) She didn't want to go private as she thought it was "snobby" but her mom (my DIL) was not having her going to the local comp, and she didn't pass the 11+ to get into the grammar (where her mom went) They thought of moving house to get in the catchment area for better state secondaries but left it all too late, so independent school it was.
She started in Yr 7 and has now just started Year 11. I was really worried that she wouldn't fit in (both parents primary school teachers) but from working class backgrounds. I think (as far as I can recall) she was ok at the open day, and liked the girls who showed them round. However she was the only girl from her primary going to this school, and didn't know anyone. She talked about "looking for girls on the bus who looked nice" but I had already sussed out that these girls wouldn't be on the bus - they would be driven, and I was right about that. In fact there is only 1 other girl in her year who catches the bus home - all the others either live within walking distance or are picked up by parents. The 6th formers mostly have their own cars and special car park!
My other worry was that most of the girls would have been at the junior part of the school (Yrs 1 - 6) and so would know each other and friendships firmly established, and again that was the case!
But DGD seemed to settle very quickly and gained so much in confidence as she was always really shy and wouldn't go to birthday parties/tea with kids until Yr 6 at primary and then she wasn't keen. But right from the start she made friends with a couple of girls who were new to the school, though one left at the end of the first term which was a blow. She was invited to sleep overs and parties and seemed to thrive. BUT all the girls (with one exception) come from very wealthy families (it's a very affluent catchment area) DGD lives on the "wrong side of the tracks" though in a perfectly nice 4 bedroomed house. She goes to their houses, and some are those massive places behind gates, some have fields and a wood at the back, and there are ponies in the paddock - you get the picture! One of her friends has a house with 15 bedrooms! DGD doesn't invite girls back to hers very often - maybe if they are going to a gig or something, but not just for sleepovers and I'm sure this is because of the difference in the houses.
I've talked with her a lot about these girls, and she admits that they all talk "posh" (she doesn't) and says "the school won't change me" - in fact it's a bit of a thing with her and I suspect she goes too far the other way sometimes. The other thing is holidays - DGD doesn't have a normal teenage life because all the girls go on holidays whenever school breaks up - ski-ing in the winter and holiday villas in the Med in the summer and all over the place. She gets a holiday but it's usually Wales and a trip to Ireland where we have relatives. She says the girls don't say "Are you going on holiday" they say "where are you going on holiday?" She says "nan they don't brag about it at all and they're embarrassed if anyone thinks they're "posh" or "bratty" - I think she's right - they don't brag because it's just normal life to them, it's what they've always known and they know no different. I remember seeing a Christmas card one girl sent at the end of the first autumn term saying "Where are you spending Christmas, I'm going to the USA and Sweden." Yeah right!
BUT here's the thing DGD is totally ok about all this, and has her feet firmly planted on the floor. She laughs about them saying "Oh I get so bored with staying in our villa - so we're only there for 2 weeks before we go to XY or Z country." She has a nice group of friends though is friendly with most of her year group, although they are all split up now as it's GCSE year. And she has thrived, without a doubt. She's having opportunities she would never had at a state school - she's very into drama and they have their own theatre, dance studio, swimming pool, hockey pitches, tennis courts etc and acres of grassy areas. There are lots of lunch time clubs that she enjoys, and all in all it's been the right choice for her. Academically she is doing very well but is conscientious about her work and revision and it pays off - plus there were only 11 girls in the form before they split up for their different options.
The plan was always that she would leave at 16 and go to 6th form college (there's a very good one near to the school as it happens) but she really wants to stay on into the 6th form and so her parents are continuing to make the necessary sacrifices to enable her to stay on. I would have preferred that she left and mixed with "ordinary kids" but she wants to stay with her friends and thinks she will get better A level grades.
Having said all that I don't agree with private education but it wasn't for me to make my feelings known. I just wish all kids could have the same privileges. Oh yes one more thing, I think it was in Yr 8 a letter came giving details of a short trip to France, stressing that this was not a holiday but was part of the curriculum and the charge was £500. So it was compulsory. There will be more trips as she moves up the school and happily I am in a position to help but this needs to be borne in mind, as a girl could feel very left out if she wasn't able to go on the "holiday" trips.
I've met some of her friends and they seem really nice girls - confident yes, talking posh - yes, friendly - yes. DGD said to me recently "They're just ordinary kids like me, it's just that their parents have got good jobs."
Not sure whether this will help the OP or not.