DH and I are considering this for secondary, having made some rushed decisions in difficult circumstances that has led us to being in catchment for a pretty underwhelming secondary school. Eldest is in Y7 and it isn't working out very well for him. Two younger children in Y5 and Y3 - obviously if we go the independent route it will need to be for all three of them.
We've run the numbers and for three children it is a pretty eye-watering number (all the independents locally are £15k+ a year). It is just about affordable but would mean a significant change in lifestyle and much later retirement (we were planning to start winding down in late 50s - it would mean working for another 10 years and would need to stop overpaying on our mortgage).
My biggest worry is that if our circumstances changed we would have very little cushion in terms of taking a drop in income. It is such a massive commitment.
I'd be interested to hear from others that have faced a similar decision. If you can comfortably afford the fees or have children at an amazing state school this probably isn't the thread for you!