You're overthinking this.
Pick one, put it in your diary, and go to it. No excuses.
In those 30 minutes of action, commit yourself to that future action. Make it easy, in those 30 minutes plan your outfit, how to get there, look up the venue on a map, plan how much cash you'll take or what cards or whatever. Whatever excuses you come up with usually, plan against them. The group will usually say how to find them in the bar or cafe or wherever, write it down.
Worst that can happen is you hate it and somehow make a fool of yourself. In front of people you will never ever see again, so who cares.
Reality is you'll be welcomed, and at least one person, if not many, will go out of their way to make sure you are included.
And even if your worst fear happened and it's a mini drama, you'll still get a win from going. You still get to feel great about trying.
And if it doesn't click or you don't like anyone, don't go to that one again. You can just never turn up again, without any consequence. You aren't obliged.