My dd1 is 'gifted'. We've had mixed experiences of provision for G and T at the 3 different primary schools and one secondary school she's been to.
Primary school 1 she attended for nursery up to year 1. The pre-school was run by nursery nurses but overseen by the reception teacher. When the nursery nurses asked the reception teacher what to do to bring dd1 on and help her with starting to read and write (she could read and write the names of all family members before she started pre-school) they were told that she was not to be taught any of it as she didn't need it until she started school
. So we ignored her and allowed dd1 to practice her reading and writing at home while sending her to pre-school to play with her friends. Then in reception she was told to sit on her hands when on the carpet (so she couldn't put her hand up to answer every question) so other children could have a chance
. We complained about that and it seemed a bit better but we still weren't happy with how much she was being stretched, so by the end of year 1 we moved her (coincided with a move to another town anyway for a new job)
Primary school 2 was a very small school with only 60 children in the whole school. She absolutely thrived there, she was allowed to move at her own pace and if that meant she was in literacy and numeracy groups with children 2 years older than her that was fine. We adored that school, even though OFSTED only rated it as satisfactory.
We then moved house again and had to change to a much bigger school with 3 classes per year. We were a bit worried about the lack of personal connection in a bigger school but we needn't have been. Having more children meant they had more clever children too and she was being challenged by some of the other 'gifted' children. She loved it, we loved it, and she was working at level 6 in Maths, English and Science by the end of year 5 although her reports say level 5 for years 4,5 and 6 because they didn't officially test for level 6. They even had a 'Gifted club' after school one day a week and online too where she was encouraged to broaden her knowledge with subjects such as Latin, Archaeology, Astronomy, etc.
She's now at secondary and is loving an subjects where they are in sets, but hates the subjects they are in mixed ability groups for. She really wants to be challenged and is being challenged when the teacher is aiming for challenging a top set, but not when the teacher is having to pitch to the middle of a mixed ability class.
She also does a lot of extra-curricular things. She plays an instrument in an orchestra both in and out of school, she's in a choir, goes to guides, attends swimming club.
Basically a state school can stretch a gifted child, or they can be very poor with it. The trick is figuring out which ones can provide best for your child. Or, as for most people, you have to accept whichever school you are allocated and hope for the best, while doing what you can at home as well.