I think interacting with someone when there is a purpose to it is a lot easier. So helping out at a fundraising activity at the school, you can hide behind the stall 'helping', but get to chat to people for a bit, but not an overwhelming amount. Volunteering in anyway, is a great way of meeting people without having to spend too much 1to1 time with them. Helping sort things at a charity shop 1 or 2 mornings a week, you talk to the other volunteers but not with the public.
I hate to say it, but getting a dog, can be great. Taking a puppy to lessons, and walking them at the park can give you the opportunity for quick hellos to people as you pass. There's one particular park not too far from us that I've had lovely 1 or 2 minute chats with other dog owners/walkers, but no one is willing to loiter. If you have a dog that gets along great with other people, you might find those chats getting longer as your dog mucks about with theirs.
Taking your DC to activities is great. Cricket is absolutely brilliant, especially if the club has club house where the parents can have a drink while their DC train, and on Sunday mornings it's absolutely delightful sitting in a deck chair with a cup of tea, in the sun (cricket stops if it's raining, unlike football and rugby), watching the game and chatting with other parents, or not, if you prefer to concentrate on the game. You can even be the scorer, that gets you out of talking to people as you really have to concentrate on the game.