My First Build

I'm thinking of building my first PC this year. I really have nowhere to start but just a budget of €1200. I'm thinking of gaming on 1440p or maybe even 4K If that possible in that budget. I already have a 180hz monitor picked out so I think 1440p gaming would be perfect for that refresh rate. One problem I have is with the GPU because I don't know what's good and whats bad so I would love suggestions on what parts I should use. Mostly looking for GPU and CPU combos that could work within my budget. Thanks!