Anna I am at the other end of the process with two DDs who went to a vert selective indie. What I have learnt from the experience is that you really have to go with your instinct in terms of what is right for your child, and not assume the further up the league tables the better.
DD1 was ambitious from the off, she wanted to apply to the most academic schools, we are in West London so she was wanting to apply to some of the most selective "hothouses" in the country. We lived overseas so naively did minimal preparation and she got in everywhere. She had thought she wanted to go to SPGS but she came out of he interview saying that she hated it, thought it was cold, unfriendly and arrogant but she walked out of the school she went to, which had something of a reputation as a souless hothouse, quite certain she wanted to go there. She thrived and they nurtured her love of Science, and gave her opportunities to develop breadth as well as depth, she is an avid reader, enjoyed drama etc. GCSE was a bit of a nadir in terms of academic challenge but that is the nature of the national exam system, they have to get them.
She didn't get into Cambridge because although the interview process is much improved, she for instance had two interviews, each with two interviewers, there are just too many bright applicants chasing places there these days, she was pooled but not offered a place. It is something of a lottery but it's a lottery only the very bright and very motivated even get a stab at. It isn't a problem, where she is now is equally challenging and prestigious for Science, has close relationships with the research organisations, and she has a funded internship this summer at a research institute attached to one of the teaching hospitals and fees waived for her Masters. She absolutely loves Science and her enthusiam has never wained. I feel sure it has all worked out for the best for her .
DD2 who we already knew was dyslexic ( and was recently diagnosed as also dyspraxic, DD1 is also dyslexic but has found her own ways around it and has never had extra time or other support) was guided by one principle in her choice of school, to go where her sister went. I felt that another school further down the tables felt right for her but she worked hard and got in and when I questioned why they had offered her a place (I did that with DD1 too as I wanted to make sure they hadn't just had a good day and might struggle) they clearly had spotted and valued her strengths, creativity, emotional intelligence. So she went there, and again they nurtured her talents, inspirational teaching in English and an impressive CV of roles in school plays (she also presumed her drama outside school, including a west end role ) BUT she really felt the pressure academically, felt that all that mattered was A*s and has developed terrible problems with exam anxiety, including panic attacks. She also felt the school favoured the overconfidant girls who seek attention and it was too easy to feel unnoticed. It was a dysfunctional year with some very difficult girls, they practically had a satellite unit at The Priory by 14, so her experience may reflect the way they handled a very atypical year and their worries about their results. She has now moved for sixth form, to that school further down the tables I thought felt right for her. She much prefers the teaching which she says is encouraging rather than pressuring, and the atmosphere and ethos. So yes we have changed course but I don't think we have backpedalled, just realised we had taken a wrong turning. I don't expect that she will do worse academically just because she is at a less selective school, they may teach differently but they still teach well.