It's done via command line, you need to install cloudflared, there's a nice guide for it here -
https://docs.pi-hole.net/guides/dns/cloudflared/
As a bit of an update, NOW TV etc is still working fine but BT sport is still poor, i dont believe they're using akamai so it could be another cache with issues but i'm still trying to track that down
---------- Post added at 15:19 ---------- Previous post was at 14:54 ----------
Scratch that, looks like BT use t1-live-euwe2-us-ak-streams-sport.akamaized.net but also seem to use cloudfront, the former appears to hit an ntl host, the latter appears unaffected and resolves to the same IP with DOH and without