Regarding Secondary schools. In the areas you're talking about, there are several state schools as well as the 2 Grammar schools (single sex provision) - Woodbridge, Trinity and Higham's Park, with Wanstead in... Wanstead. Woodbridge is where DD went, it used to have a terrible reputation but money has been poured into it and the then Head did a brilliant job of raising standards. The new Head was rather thrown into it by the pandemic, but he has been really great. Specialises in languages, you can choose from French, Spanish, German or Russian (pre-covid there was a yearly trip to St Petersburg)! Great Music, Drama and English teachers, but not so hot on Maths or Science teaching imo. I'm not sure how far really bright children are stretched. Pastoral care was excellent - DD has dyslexia, dyspraxia, ADHD and anxiety and they really looked after her. I'm rather sad that she hasn't chosen to stay on at their 6th form, but it didn't offer the subjects she wanted. Lots of extra-curricular activities and opportunities if your child wants to take them.
Further into Clayhall and there are Caterham, King Solomon, and Beal. Beal is an academy school and it had a good reputation, but there has been a lot of violence there recently and I know that it has suffered with homophobic bullying. Caterham is a specialist sports school (it has its own swimming pool), but has fairly lousy results; although my nephews and nieces went there and have all done well, so I daresay it's down to the individual child. King Solomon is a religious school, although many of the children are not Jewish - Clayhall was a very Jewish area until about 10 years ago, now it's far more Asian and the school has changed its admission policies. A friend's DD was there until this year and absolutely hated it, one of DD's friends is still there (moved from Beal after said bullying) and his verdict is 'it's okay'. Also parents are expected to tithe on a monthly basis!
Re. Wanstead High, DD originally went there and I had to move her in Y7, at the time (4 years ago now) their discipline and bullying was terrible and they were in denial that there was even a problem. There were also issues around teaching and SEN provision - DD, who doesn't like school much, said she wanted to leave because she felt like she was forgetting stuff she already knew!
Trinity, the Catholic comprehensive, used to have a very good reputation, lots of people faking church attendance to get in, but I'm told it has gone downhill of late. I've heard really good things about Highams Park secondary but I don't know anyone who went there.
The grammar schools are meant to be good, I know several parents at the girls one (Woodford County High) and they were a bit non-committal about it, despite having tutored their children to the nth degree to get them there - the main issues I've heard about are the dilapidated buildings and that it's rather monocultural.
I live in Ilford! Been here 32 years, and it's not all terrible, although the council seem to be committed to making it worse by nodding through every backyard bungalow extension and crappy flat conversion going.
South Ilford is pretty grim - because the housing is relatively cheap it's also got a lot of deprivation, but if you're used to Hackney pre-gentrification then it's not that terrible. I live in the North bit (Off The Drive, as the estate agents call it) and you get a lot of house for your money, big Victorian double-fronted terraces. The Cathedral estate is more 1920s/30s, semi-detacheds with garages. Our neighbours are (mostly) lovely and there is some community spirit but it's definitely not along the middle-class likes of Wanstead, Highams Park or parts of South Woodford. We have a cinema, a theatre and a new arts centre which is pretty whizzy and the coming open-air food market looks like it's going to be really nice. There's also the new Crossrail coming through.
However, one thing that no-one will say directly, and it may or may not influence you, is that it's very Asian. It was a reasonably equal mix of ethnicities when we first moved here, but over the years it has become more and more Asian, specifically Muslim. This may not be an issue for you, it isn't for us, but I know when most people say 'eww, Ilford' it's basically what they mean. However, we have gorgeous parks (Valentines and Wanstead), a relatively decent shopping centre (although Westfield and lockdown has killed off a lot of it) and the transport connections are amazing. We have lots of restaurants, several of which are decent, and a few independent coffee shops as well as Costa and Starbucks.
It's also a ten minute bus ride away from Wanstead, so you can actually afford to take part in the coffee culture if you're not paying their housing prices!
Sorry, that turned into a bit of an essay...