I am guessing you will not be on a Corporate BES. With that said there is no easy way to address stopping email. The BlackBerry has been designed to not play a tone / alert you when you choose but the data still flows.
It sounds like you are just going to be stressed knowing there are unread emails from work. You can't set the device to only grab when you want it. The BlackBerry was designed for people who want instant communication.
If this is truly an issue for you a Windows Mobile device would probably be best.