Block data but enable MMS messaging?

I really want to block data from my phones so I am not charged extra for something I will not use. I currently have the $30.00 unlimited txting plan, so I want to send both SMS and MMS messages. Talking to people and At&t clients they have said that it is impossible to block internet and keep MMS messages but I feel there is a way to hack or tweak with settings so internet is blocked, yet I can still send and receive pictures, videos, etc via text.

The reason why I want to block data is mainly because in the qwerty keyboard the email, medianet, and IM button are there and I may accidentallly press these buttons while texting. I don't want to be charged extra for something I do not want and was on accident. Please help!!!