Oh God... have DS in Y4 and just taking head out of the sand to start thinking about all of this, and these 3 schools are ones that come up in discussions.
Can I be cheeky and ask: do you have tutors/ self-tutor your sons?
DS is Level 6 in Maths, Writing, and Reading according to his primary report...but I understand that half the battle is exam-technique (no matter how much schools try to combat this). We've started setting him VR and NVR problems from the Bond books...but some one had said if we are considering grammar schools, we need to get a tutor. And if you go down the tutor route, you need a tutor for each subject!
DS is my eldest, and most of his peers will be going to our good local comp...I feel very under-informed, and would welcome any tips/advice!
Some people do get a tutor for each subject and pay weekly tuition bills for 2+ years but this is very much the extreme. Most people tutor for a year or so and many do it at home themselves with past papers and books or pay for just one tuition session a week for that time.
It would be wrong to say tutoring for those schools is rare - it is very much the norm even for children who are expected to absolutely fly through the exams (so many children take the exams that the required scores are very high and mistakes or nerves might make a difference).
If your DS is level 6 in Year 4, he will be in the 'expected to absolutely fly through the exams' category but it is still normal in that situation to do familiarisation exercises and fill in any gaps.