Thank you for posting. If you take a look at - Learn about BT Sport and BT Mobile you'll find some more details around adding BT Sport to your BT Mobile.
Can I get free BT Sport with BT Mobile?
If you’ve got a BT Mobile plan costing £15 or more a month (with Broadband discount), or £20 or more a month (without Broadband discount), you’re eligible to get BT Sport included on your mobile plan.
You’ll get the BT Sport app on your smartphone only. This means you can't watch it on larger screens like a laptop or TV. And you can't Chromecast/Airplay BT Sport content, or watch it on the web player.
Sign up now at www.bt.com/sportonthego >
Once you've signed up, it'll take up to one working day to get you set up.