If you do not have an ESPN+ subscription, there is the option of a bundle that gives one year of sporting fun, which needs you to pay some amount. You have the option of getting a whole pack, or you have the option of having separate bundles. However, paying for a full kit is a lot more cheaply than having to get them separately. Getting a kit is what most people go for if they do not have ESPN+. You can watch live UFC fights without having to go to the watch it physically.
Unfortunately, you won’t be able to watch UFC 252 in the BT Sport. Perhaps you haven’t known this yet; the BT spokesperson confirmed that BT company would end the relationship with the UFC on December 3rd. That means BT Sports will no longer broadcast the UFC events on the channel. The UFC 252 event happens on Saturday, 15 August, 2020. But you can still purchase the PPV through the service.