It's very unlikely that the repair shop will go to the trouble of restoring a drive that's had even a cursory wipe with a cleaning utilility - unless you work for the FBI and there's something really good on the drive.

I'd make sure you have two or three backups of your stuff, with at least one in the cloud, make sure you can do a restore, then wipe the personal stuff from the drive.

What would you do if your drive died anyway? You need a secure backup strategy, so you may as well get one now.