I am not the ideal person to answer but I see you have 50+ views on this thread and no answer so thought I would just respond a little.
My elder two are at a very selective grammar.As it is so selective, it is heavily fed by prep schools and most parents I have ever met had indep schools amongst their back up options.Therefore although it is a state school, it would be truthful to say that I have barely found parents truly in our sort of income bracket.There are a few and I imagine there would be at Habs because there would be other bursary/scholarship students.
There are times it is difficult - birthday and Christmas presents can seem stingy compared to some of their peers.However there are also wealthy but sensible parents who do not wish to spoil their children.We don't do skiing trips or their like.In fact they don't even bring the letters home now.
I say to them that if they work hard, that is all for them in the future.It isn't real hardship in the grand scheme of things. They have basic mobile phones when some have iphones etc. All that said - they are not completely alone in "getting less" and as they get older, they understand the reasons why things are as they are.
We have visited some dauntingly lavish homes but no one has ever been anything but gracious to my children.( or me)They get judged on their behaviour and manners which are good.(outside anyway
I would think carefully about early entry.It was suggested when we lived elsewhere for my eldest.Unless she is very old in her year - a years difference socially can be a lot at certain stages.
Go and look around the school and see what you think of the "feel". It can be very telling!
I am sure someone infinitely more qualified to post will come along soon but good luck.