Ok. You've set up the PC to automatically log in on boot up, see here.
On 'sleep' however (closing the lid), the PC doesn't power off so you need to change the settings as here .
Personally I think its a bad idea for such a set-up. Not only for security reasons but Windows is set up in a way that security is first and foremost the OSs settings. You could get a hiccup and not being allowed in to your profile.
I always create a second admin user on a PC/Laptop just in case of a profile failure and always use a password.
Just my humble opinion, though.