Last month O2 became the first UK operator to directly sell the OnePlus 3. That deal seems to have worked out well for the two companies, since they're doing the whole cooperation thing once again for the OnePlus 3T, which became official yesterday. O2 will be the exclusive operator partner for the OnePlus 3T in the UK. It will have the phone in stock on its European release date of November 28. Pre-orders are set to start tomorrow. You can buy the handset outright, thus having to shell out £417.99 for the 64GB version or £456 for the 128GB model. Or you can pick an O2 Refresh...
Source: http://www.gsmarena.com/o2_uk_will_sell_the_oneplus_3t_too_preorders_start_tomorrow-news-21673.php