For the UK could you also consider some Navy Lark types?
Britains had a "Herald" range of home service troops that were fairly generic looking. About a dozen poses if I recall correctly.
Apart from Quatermass, don't forget books like the Midwitch Cuckoos or 1984.
You get quite a few old programmes on R4extra.
For the 1950s US civilians, will there be Jets and Sharks?
And if you need any rules testing I'll volunteer the school club again.