iCloud vs Time Machine Backup
I currently have a 13 inch MacBook Pro (non-touch bar) and was notified that it was eligible for the Solid-State Drive Service Program due to the indue that could result in dat loss and drive failure. Before taking it in for service, it says I have to back it up and mentions Time Machine. However, I currently do not have an external hard drive to back it up to. My laptop is currently backed up to iCloud. Is this enough for a backup or do I need to get a hard drive and use Time Machine?
MacBook Pro, macOS High Sierra (10.13.6)