Liz - you might wanna consider moving this post as I think it's something that's been an issue for many of us, not just those with kids?
Anyway, I also had a hell of a time making friends when I first moved here and in fact it took me quite a while to get over that.... I think one problem is age. I found that even in California, the older I got the harder it was to make new friends - people develop groups of friends and have long-standing friends and just don't go out of their way to make new ones; and they have jobs and kids and busy lives and fitting in new relationships can just require effort that they don't have time to make. The other thing to keep in mind is that a lot of British women are a lot more cautious in making friends - they're less inclined to just automatically want to be everyone's friend, and in some ways now that I've been here a while I can sort of understand that as not being such a bad thing....
But in the end there were a couple of things that helped me. Number one was this board and one other that I used to use. I managed to find a group of Americans living in my area and I really just hit it off with a couple of them. The other thing is to get as involved as you have time to with stuff in your area - take a class, spend a lot of time in the garden (once it warms up, that is!) and talk to your neighbours over the fence, if you have a day a week to volunteer or even get a part-time job you'll start meeting people.... I found that working at a crummy little retail job on my local high street opened up a whole new world - people say hello to me on the street now.... And you're very right about things not developing overnight - and you may have to meet a lot of people before you find one or two who you truly relate to, but it definitely will happen!
I take it your dh isn't English? I've got quite chummy with the wives of a couple of my husband's friends.