I have an old T400 which I use as a TTY cient, that I can SSH into if I need to. It has 8g ddr3 ram and I popped in an SSD, it can even take a second harddrive if you take out the CD tray!! It only cost me €20 second hand.
But really, if you're using the laptop as a console client, just look for a laptop with an internal SSD and that has a minimum of 8 gigs of RAM. Make sure the parts are easily interchangable as well, older thinkpads are perfect for that imo.
I can resonate with feeling lost when first starting out with Linux. If you like learning from books, I can recommend the "Unix and Linux system adiministration handbook" by Evi Nemeth. It includes information and tips on all things Unix/Linux, including step by step tutorials on home to set up a media server etc.
Get used to Linux and keep persevering, you got this! :)