I have a Windows 10 PC which I need to keep backed up. It's a headless system and I access it via RDP - All I need to be able to do is have an external HDD plugged into it and have it run a full backup once a week or so. I want the backup to be something that if the internal HDD fails, I can simply remove the external drive from the caddy, take the PC apart and plug the backup drive in and switch it on. The backup needs to be a real set it and forget it solution. Free software would be good but I don't mind a very small one off cost. Any suggestions please?