Thank you all for the help. I live in Leyton, work in Limehouse, but would not be unwilling to go elsewhere if there were somewhere I could find people to be with that are my age.
The main trouble with finding people is my age. As a 19-year-old not going to Uni, I am much younger than my coworkers (some of whom have CHILDREN my age!) and am not part of the University life. I am looking into enrolling in some short courses, but I fear that they will still be populated by professionals and people much older than me, as people my age are doing undergraduate work.
I already play on an amateur football, which I absolutely love, but still, the majority of the players are much older than me and we don't see each other outside of football. I would love to find more athletic activities to do, but just don't know where to look. More football would be awesome, but I'm an athletic person, so anything would be enjoyable for me.
Thanks for the help, and hopefully you have more ideas!