Hi Jussy (and everyone else!) --
I'm a newbie here on mumsnet but it's about time I started meeting people.
We moved here a few months ago from overseas as well -- husband here for 2-yr job stint. I'm a SAHM and in your area. Ds is 3.5 and a bit lonely from moving around etc., and because this immediate neighbourhood doesn't have enough mums&kids I've met yet, but he's a sweetie and I'm lucky in that regard. I need to meet other mums/playmates and make some friends. My location is good for the shops & station & buses (i.e. convenient for dh's commuting), for the Richmond Green & Park, & the Old Deer Park playground, etc. Our address sounds posh, but flat is tiny and surrounding streets appear to have only pensioners and/or rich people who can't be bothered. So I could use some company with regular people! With kids and everything!
Plenty of mums & kids going by near here every day, but generally everyone seems to be on their way to somewhere else (like the shops), since Normal People don't actually live here, apparently....
I have no car, but lots of buses about going in all directions -- Sheens, Kew, Twickenham, Kingston, Putney, etc. And trains. So I can get about (at toddler speed), but need places to go, people to meet, things to do.
Also what sort of school/nursery ideas make sense for a 3.5 yr old who will be here just 18 more months -- and on a moderate budget (more moderate than a Richmond address probably usually implies, I gather!). 
(this is not quite the sort of neighbourhood we live in back home...)
I, too, come from 30-something latitudes and have found the absurdly short winter days here a bit dreary. A bit like spending several months in a dimly lit refrigerator. 
'Course the summer days will be absurdly long!
Anyway, I'd love to hear from anyone with 2-4 yr olds around the Richmond, Kew, North Sheen, East Sheen, St Margarets, Twickenham, Ham, Petersham, Kingston, etc. etc. areas. Hey, west London generally...
Thanks!