As you're giving your laptop to your son, rather than to MI5, a fairly basic bit of wiping should be all that's needed. Simply delete everything in 'Documents', 'Photos', etc and uninstall things like banking software (and, indeed, any other software which might only be licensed for a single user or which might have stored passwords).
[Note: If you think it possible that your son might be tempted to try to recover your deleted files, simply 'destroy' them, instead of just 'deleting' them, by using File Shredder:
https://www.fileshredder.org/ ].
Then go to your browser(s) and delete any stored passwords that you might have there. (Instructions for Chrome are here
https://www.techrepublic.com/article/remove-saved-passwords-chrome/ . Instructions for other browsers are easily googled). Similarly delete all your bookmarks. [NB: DON'T just uninstall a web browser. That can often leave your profile file in place, which will get loaded up again when anyone reinstalls the same browser].