As scheduled, carrier O2 has started selling the OnePlus 3 smartphone in the UK. You can purchase a unit for as low as zero down followed by 24 monthly payments of £28 each. The plan includes 500MB data, unlimited texts, and 500 minutes. If you want more data, there are plans that get you 1GB, 3GB, 5GB, and even 20GB data, and carry a price tag of £32, £35, £39, and £44 per month, respectively, with no upfront fee. The device is also available on the carrier's Pay & Go deal, costing £336. It's worth mentioning that O2 currently only has the Grey color option in stock. Source
Source: http://www.gsmarena.com/uks_o2_starts_selling_oneplus_3-news-20814.php