I want to stream on twitch but my connection is pretty bad here in Ireland. So I thought, will getting it wired fix this? And btw I will have to use power line.
Wired is always the best, and most stabled internet connection. Linus did a video on powerline connection, and he stated it was about as stabled as a long Ethernet connection.
I guess you are currently using wifi which makes your connection bad? Or is it you internet connection in general?
Wiring it up will help in the case you're using wifi, even using the powerline via adapters will give you an improvement.