When we lived in London (zone 3), we went to our local park once or twice a day (twice = morning and afternoon), so DS grew up walking and scooting a lot more.
All our ante-natal friends were there.
I went to sewing classes once a week. (There was local childcare available: nursery and a drop-them-off playgroup)
There was excellent transport, meaning people could come to our local centre for the market and shops (very good haberdasher, so I made lots of things for us/presents), local tradespeople so things could be repaired (e.g. mending jewellery, re-soling shoes, cheap "ethnic" food). There was no stigma to charity shop-shopping, nor to second hand children's things; rather, there was an extremely good periodic table sale which was utterly middle class.
We have moved to the 'burbs, where, by contrast:
- there is a LOT more driving, and the "countryside" is actually a PITA to "access", given the faff of driving and parking.
- we have to make new friends, which is not only a matter of trying to connect with people but with opportunities. Also, gievn that I didn't join an antenatal group for DC2 (longer DH commute, no reciprocal childcare for DS), my poor DD has no friends her own age, whereas she would have had a ready-made network, if we had stayed in our old place.
- this suburb is a bit of a "black hole" for courses and activities, for me and for the DC
- the local high street is pretty blighted, especially with some larger centres nearby which draw all the shoppers
We had friends at various income levels, and I think that heterogeneity made it less "essential" for parents or children to "conform" (though there was a certain amount of conformity, e.g. in breastfeeding)
I hope that didn't sound like a moan; I was trying to be analytical. Basically, our quality of life is considerably poorer here despite our having a garden and larger house. In fact, the garden is emblematic of the problem: people entertain at home, rather than meeting one another at the park, so how do you meet people in the first place? (school, I suppose, but that's been slow work, too)
You're going to lose all the networks of your existing life, so the new place had better be worth it. I agree with previous posters about trying out a setting before committing to it.
As for "outdoor values" things for your kids to do, could you afford summer camp in the US one year? I did that as a child ("Interlocken", in New Hampshire), and it was a paradise of communal cabins, lake-swimming, drama, tree-climbing, instrument-building, sports, etc. A lot of the counsellors were pretty hippyish, meaning we had new role models. There were the usual "cool kids", of course, but enough of the "other" sort for there to be a genuine choice of friends.