Honestly I would say forget about pugs for learning the basics, they are ok for a while if your level is high enough but they are not the best representation of a real, actual TF2 match (most of the time games are unbalanced because of difference in skill, there is a big focus on individual DM instead of teamwork, etc...)
The best way to learn and improve in the game is just finding a team of like-minded, similar skill level players who are commited and willing to learn and improve, be it doing demo reviews, map talks or just scrimming together multiple times a week. It'll may suck at first if your skill is not enough but with sufficient time and dedication you'll notice how the team improves and the game becomes more fun and easy to play. Of course it's not always that simple to find a perfect team, especially in this silly community, but for the little I've seen on your streams you seem like a chill and dedicated player (also brit) so it shouldn't be that hard with a little bit of luck.