DH and I are not sure what to do for the best with DS aged 7. He is at a good primary school with a wonderful head teacher who has really turned the school around since she joined a few years ago. He enjoys school and finds the work easy on the whole, but is not really interested in doing more than the minimum to get by. He has also had issues with sometimes severe shyness (mostly out of school) which has been assessed by the borough special needs psychologist - she thought it was not likely to be ASD or outside the normal range but wanted to keep an eye on him and review once he joined the juniors (the infant school is separate).
We are considering sending him to an independent school to help with his confidence, and to stretch him academically especially in weaker areas such as English. He has been offered a place at a very small selective independent with only 11 children in his year group. It has an excellent reputation for getting children into local superselective grammars and independent schools but is limited on other facilities, e.g. sports, IT, library etc. The other school is a more well rounded traditional prep but focuses on independent school entry so he might need additional tuition for grammar entry.
We can afford the fees but have 2 other dc and would find it a stretch to have all 3 in private education. I am also not especially keen on private at this age as the state primary actually has better facilities, extracurricular activities etc but I worry that he will not develop in confidence and reach his potential if we don't move him at this stage.
Any thoughts?