Data Sim for Samsung Tab Pro (12.1)?

Hi

I have a Samsung Galaxy Tab it says model SM-T900 when it starts up and is the biggest screen size. It was bought for me as a present a few xmas's ago.

I've always used it on my home broadband but I'm changing suppliers and will have no internet for up to 23 days. I wondered if I can buy one of those data SIMS I've seen on ebay (seen one where you got up to a year to use the data included then just use it PAYG).

I'm not sure if any of the slots around the side are for a Data SIM and wondered if anyone knew if it took one? I can't find any mention of one in the general settings, it only mentions Wifi and SD cards?

Also if that wouldn't work..I have an old Samsung Galaxy 4 phone. I had lost it so it it had been blocked and the SIM blocked but it has been handed back to me. How do I unlock it so I could use the data SIM in that instead then maybe share the connection with the larger tablet?

Thanks very much

Leigh