Welcome to this user forum.
Which mobile phone are you using? Where in the UK are you located?
Until someone more qualified arrives, can you advise whether you are using a VPN? I know from experience that using a VPN, whether you are in the UK or not, is not possible.
If you are experiencing VC003, then yes, we are blocking BT Sport streaming due to seeing your device IP address as being outside of the EU 'or' there is an app on your device which has a built-in VPN which you do not know about and is masking the true location of your device.
It is also possible that BT have blocked the IP address you were using at the time for reasons such as Elite Proxying but you can gain a new IP address by restarting your router.
I think, looking at the email address you used to register on the Forum, your issue has self cleared and is now working which is good.
We will look into the reason why it didn't work to start with