This is a minefield: as far as I know, if you leave your employment, you are supposed to cancel your work permit with the Ministry of Labour AND inform Immigration both, within 24 hrs. While some do not bother to do this, you are theoretically in breach of your permission to stay, which could cause you problems if you want another WP in the future. It's unlikely you will be stopped leaving the country, because Immigration doesn't know or care what goes on at the MoL. If you do manage to do what is required at the MoL, at the Immigration Dept, you will be give seven days to leave the country.
I've never heard of any way round this, so your best option may be to make arrangements to go to Phnom Pen or other regional city, get a TV and return, then make arrangements to get a study or volunteer visa.