I've not read all the responses as I don't want to get the rage.
Our children go to a similar sounding, not outrageously expensive, single-form entry private school.
The school has a tremendously happy atmosphere - it's like one big family.
We didn't 'choose' it but due to work were forced to move very quickly and could not get state school places for the children. Or we could but it would have meant two different schools (in special measures) 10 miles apart, for children in Year 1 and Reception and 3 different school runs.
We've never looked back. Children are so happy and the smaller class sizes make all the difference.
At risk of incurring the wrath of MNs the standard and level of education is much higher than in the state sector.
Not because of better teaching or because the school weeds out SEN (it doesn't) but because right from the start they are getting the children to focus on reading, writing and maths.
My 4 year old had no interest in reading at all and said she found doing work 'boring'. In some settings with 30 noisy kids she would have spent the entire time playing.
With a firm (but kind and lovely) teacher, she is now in her final term of Reception, is loving reading every night and producing beautiful pieces of written work.
After a year in Reception in the state sector, my 6 year old couldn't read and write at all. She found school really boring and not challenging. (She was in a school ranked outstanding). She started Year 1 in the private sector and I was worried that she would be behind. Now she is top of the class for maths is on Stage 7 ORT and her handwriting is wonderful.
Of course it's not all about academic achievement but in the private sector you have smaller class sizes (DD5 has 17 in her class, DD6, 22) and it really helps when every single member of staff knows who your child is. And all the pupils know each other too and you see Year 6s happily playing with and looking after the little ones as though they were siblings.
Only you know what is right for your child but I would say go for it. I'd also not worry about them going to state secondary. 50% of the children from our school go on to state secondaries and integrate well, I am imagining that ours will go to a state school too, for financial reasons. Fees really jump.
But many people say that if you can only afford prep school go for it, because you are really setting them up with great learning habits.
My eldest DD is at secondary school having been at a private school and is absolutely thriving having had that good start.
Let the slating commence...