Anxiety and getting out with kids

Hi Mums
I recently moved to a small town where I know only a few people through my husband. I suffer from anxiety. I have two kids aged 1 and 3. My anxiety is fine when I'm doing things I know or with people I know. (work family friends familar environment) Some would even say I have great confidence and wish they could be like me. Ive even signed up for a local community group to help starting in February and that doesn't bother me. But when it comes to kids activities it's a completely different story. My confidence is gone, I freak out I get so anxious; especially if I don't know someone or how something works. I don't want to hold my kids back because I'm to scared to leave the house. Before we moved my friends had babies and this stuff wasn't an issue because I've always had a group to do things with (play dates, pool etc)
I've just enrolled my eldest in swimming lessons and even though its not due to start for another month I'm already freaking out and over thinking it. How it works, what we have to do, who will look after my youngest and the biggest thing what will people think of me, will the kids and I fit in) That's how I've been thinking with all activities (playgroup gymbaroo etc) I want to attend activities for my kids so they make friends and socialise my hubby isn't always available to help as he works 12 hour days week on week off. (Though he does try to help when ever possible because he knows I struggle)
I guess what I'm asking is please can I have some tips or advice on how I can better manage my self for the kids sakes.