For moments of desperation https://www.reddit.com/r/soccerstreams/ almost always has a semi-decent stream.
If you want to try a bit harder you can use AceStream (a p2p stream client) which is basically a modded version of VLC. Pretty easy to use instructions here: https://www.reddit.com/r/soccerstreams/comments/82ac7j/acestreams_you_what_are_they_and_do_i_use_them/
The only hard part if finding the streams but I think I've found a reliable source here: https://acestreamsearch.com/en/
Just search "bt" and find the appropriate BT Sport channel and you're away.
Quality if far is better than any dodgy in browser stream you'll find and from what I've seen better than plenty of actually legit payed streams (7-10 Mbps).
Screenshot of current results:
