how to use home sharing without internet?

I have set up a wifi network but i only have internet via sim card where i live, it's a little bit remote.

I bought a broadband router just to create a wifi network as the exchange where i live does not provide broadband.

Purchased an apple tv and HDMI cable as i want to stream media from my computer.

I get to the sign in but apple tv wants to access the itunes store and thats where it ends.

I'm so close to finishing the set up. Anyone have a work around?

I could use my iphones hot spot to sign in the apple tv if it only needs to be registered. (I'm not at home for a few days so i will try this when i get back home)

Thanks in advance for your reply.