How can I find hobbies and side gigs outside work in London?

Hi all,
I've started my first full time job in London post-graduation and post-gap year and not only have I lost most of my friends, but I also seem to have lost track of my hobbies and side gig incentives.I live in a residential area where nothing much happens, away from the hustle and bustle of central London, and I work close-by. Although I am satisfied with my job, I would like to do something else apart from work, such as a hobby through which to meet new people, and also start a side gig to help me financially, as living in London is tough. I don't want to use mobile apps for social gatherings with unknown people because they are very shady and awkward. Apart from charity organisations and support groups for the elderly, people who suffer from mental health issues and church, there aren't any other opportunities to meet new like-minded people in my local area. This weekend I've just realised that I've done nothing else apart from going to work for the past five months or so, and it's shocking as I am a young adult and I should be having loads of fun in my early 20s instead of living like a retired woman. :smile:

Do you have any suggestions for me re how to find hobbies and meet new people outside of my full time job in suburban London?
Thank you very much! Any suggestion will be appreciated!