I'd try the South Wales Valleys. Places like Tonyrefail, Talbot Green areas or just up in Thomastown, Porth, Williamstown ect. They are close to the M4 on junction 32 by car, junction 33 is Cardiff city centre.
Good train and bus links in to Cardiff City Centre also if you have no car. Shop wise all within walking distance or a small business route, many of them have a Asda or a Morrisons as a central point to the little high streets.
They are peaceful old mining communities. Mix of youg and old families. Lots of Welsh government play schemes and clubs, museums are free, prescriptions are free. Flying start schemes and local library play groups are popular.
Petty crime can be high in some of those areas think minor shop lifting and cannabis growing operations but nothing aggressive or likely to get you or your child killed or verbally abused at all.
I've lived in one of those communities, we even left one house we bought vacant for a year, nothing happened to it at all. They have their characters, but nothing untoward. I can go running alone at night and have never felt "in danger", I can also take the dog for long walks up the mountains or down by the river banks and again feel safe and fine.
One thing, the kids are permenantly out and about playing. Like seriously constantly with the footballs and the screaming up the back lanes of the terraces but hey are kids haha!
You probably would get a 2 bed terrace for about £40k.