We're in a very fortunate position because we had a lucky windfall when DD1 was just born, large enough that we were asking ourselves, what could we spend the money on that we value and would make a noticeable difference to our lives? Education is one of our top priorities, and plays such a big part of our lives that it was one of the obvious things to put our money towards. (We don't spend on luxury holidays or expensive cars even though we could afford to, because it just doesn't interest us).
DD1 started in reception at a small prep school this September, and she was at a private pre-school for 2 years before that. It's been a great experience so far, she is in a class of 11 girls, with a qualified teacher and a TA. She has specialist teachers for PE, French, ballet, music. The food is excellent and she does three after school activities (run by external providers, the outside classes get booked up and it's nicer for her to be able to do them on the school site and get home earlier than she would if I had to ferry her to them). She does PE every day and the pace of academic work is much faster than at local state schools. The 11+ results are excellent, and I'm happy that they prepare the pupils well within school and that it will be something that is normalised in her cohort, rather than being one of the few children in a state school going to a tutor for 11+ prep.
DD can be shy and quiet especially when she is new so the small class sizes have really made a difference and she would have been lost/ignored in a class of 30. It's nice to be a parent at the school - it's not a networking type of place, but there are no conflicts of the type that my friends complain about with other school mums. And it feels much less paternalistic than state schools - no nagging about attendance or uniform rules, it's just taken for granted that all parents want to support the school and the school supports parents with excellent communication, lots of advance notice for events, holding meetings very early (before 9am) so parents can attend before work.
The school is small and friendly and I wouldn't have considered the 'state until 8' route because I like that it's a nice community where DD has started at age 4 and will stay (all being well) until she leaves at 11. It was hard enough having to leave all her lovely nursery friends! We've also moved house to be close to the school (5 min walking distance) so it was nice to settle into a new area with a plan to stay until my DCs have all finished primary (and possibly secondary, as it's within easy bussing distance of lots of excellent private secondaries). It would also be a more stressful school run to have a younger sibling at a state primary and then the older one at prep.