Simcard and Internet for Tablet

Hi

I would like to buy a AT&T prepaid simcard for my tablet. I live in Eueope though and would like to have it before coming to the United States. Can I order it with you or do I have to order it via a 3rd party?

Also, for the three months that I am in the US I would like to have a prepaid internet flatrate with this simcard. Do you have any offers like this?