I have a Samsung galaxy sIII so connection of your tab should be the same I think. If so, you have 2 options:
MHL Micro USB to HDMI Adapter c.£20 as mentioned, and
c£50 for the WiFi gizmo from Samsung - Samsung AllShare Cast Dongle.
If going for the MHL option make sure it's Samsung original as they have done something to the USB config meaning fakes/non genuine Samsung items won't work.
I have tried both and would recommend either as they both work well, but prefer the dongle as you can operate your phone/tab from the sofa. With the MHL option you are restricted by the length of cable which means you would need to position your tab/phone close to the tv and have access to a 240v power supply too...it uses your phone/tab mains charging plug.