Struggling to meet new people

I (M20) recently arrived in the United Kingdom as I decided to travel from Canada to have a change of scenery and see more of the world. As I don't have much money, I am woofing around places to have a place to stay and be fed without spending a dime. However, I am having trouble finding occasions to meet new people and I am wondering how I can fix that. I spend the week working and have the weekends off but I don't have a place to stay in a big city so I have to come back before around 8pm since the last bus leaves around that time. Anyways, I am wondering if you know how I could make friends to spend time with on weekends and to crash at their place so I can experience UK pubs since I haven't managed to go to one yet.