I would try to "do" one or two things like look up the group on the Web, see if you can find a phone number or site/e-mail address? I have trouble with phones too. Maybe you can go there "early" and just practice going? Sometimes that works for me. Do you know/like whoever you met to volunteer? Can you sort of talk to them, get them to "help" you get there? I sometimes do that. But sometimes just moving toward something helps me, if only for the next something. If I can get a bit further this time than I did "last" time, that's a success?