I don't play hoi, but I picked up EU4 from watching a lot of streamers. Are there any decent ones out there to watch? They don't have to be super active, I imagine the ones from a few years ago should be okay enough to get you pointed in the right direction.
Edit: I don't know the timeframe well enough, but is Ireland a decent place to try conquering/re-subjegating? It's called noob island in the CK and EU communities for a reason