Yes we moved from London to a small town.
It coincided with us having small dc so I don't know if I would have encountered similar issues anyway. But I have found it hard to make friends. It took longer than I thought.
One of the main differences for me is that it's such a small place. Everybody is connected in some way so you do have to be really careful about what you say and maintaining confidentiality, even if you don't think that person would be bothered by you sharing a story or you don't think they know the person. Things get passed on, exaggerated and it can come back to you negatively. Also if you do have a run in with someone try and keep your cool and deal with it as calmly as you can because unlike London where you'll probably never see them again, here you'll see them every day forever it seems.
Personally I find it easier to make friends doing activities/courses/jobs for myself rather than at the school gate. That way you're with other people for a few hours and have a chance to get to know them. I have a friend who was much more active about joining in with things than me and I would say she has settled more successfully than I have. She does choir, book group, running club, church, helps out at toddler group. But I've always worked so not had as much time.
I am on good terms with the parents of my dc's friends. But I find a lot of them already have friends and aren't that interested in making time for new ones. As such they're more acquaintances really but they're all very pleasant.
All in all it's been a great move for the dc. To them it's home and they do fine at school with friends etc. I have a few really good friends now but it has taken several years. Mine are from a toddler group, a college course and a job. I'm lucky in that I was able to maintain friendships with people I knew in London as well as we're not too far away.
I'm sure you will be fine. I hope I haven't made you feel worse. I was trying to give you tips more than anything. Be pleasant, friendly, join in lots of things, have a strong backbone (because you will encounter people who are difficult) and keep going! Good luck.