I live in and raise my kids in Thornton Heath. Rough, yes, in parts. Lots of new people with money moving into the area. Some roads I wouldn't touch with a bargepole, some crime but not really any different from other S London areas, imo.
Positives - subway, superdrug, one nice restaurant, a really nice Costa, great chinese takeaway, good schools, some outstanding, a great leisure centre, brilliant housing stock, Weatherspoons, westfield on its way, cheap housing, 22 mins from Vic, and, get this, thornton heath is filled with FAMILIES living in actual FAMILY HOMES. It's probably the most family dominated area i have lived in in south london. We have a great carnival each year with a great turn out. It is multicultural, with all groups getting a long. I'd sooner raise my kids here that some boring commuter town.
You can still get roomy family homes in Thornton Heath for under 400k.
I'd sooner TH than South Norwood, much of south croydon, mitchem, west croydon.
We are happy, feel safe, and will raise our kids here, no matter what their age. And despite the post code, I feel very much a part of South London, in the heart of it really.