Minifree Ltd (based in the United Kingdom) sells secure, high quality computer systems with Free, Libre, Open Source Software (FOSS) pre-installed. Libreboot BIOS/UEFI replacement (based on coreboot) and encrypted Debian GNU+Linux OS pre-installed (KDE Plasma desktop environment), with full driver support, or other Linux distro / FreeBSD / NetBSD at your request. These machines are intended for security-conscious people who also believe in the ideals of the free software movement, and want something easy to use. Perfect for privacy software like Tor Browser or Tails; you can also run Qubes OS on these machines.

A pretty good guide to picking second-hand laptops.