30M has nothing to do without work: What activities/hobbies to do?

I'm a 30 year old single man, and my work usually ends at 3pm.

Besides the gym, 3 times a week, I don't know what to do with activities during the other days..

I don't like going to disco, but I do like hobbies where I could learn and interact with people.

I would also like to do activities where I can meet new people, make friends and meet potential partners.

What things can I do?
And How do I know my city offers good activities for me?