Back in February 2020, streaming service Crunchyroll revealed they were able to provide users outside Toei America’s main territories (US, Canada, Australia, New Zealand) with access to a number of episodes, including simulcast, for One Piece. This included the United Kingdom and Ireland, after years of dealing with no proper legal access for the streaming side.
However, back then there was only access to episodes 1-325, which cover the East Blue, Alabasta, Sky Island, Water Seven and Enies Lobby story arcs, and episodes 892+ which focuses on the Wano story arc.
Fast-forward to present day, and Crunchyroll has finally confirmed starting Sunday 16th May 2021 that the United Kingdom, Ireland and Nordic territories will be able to watch One Piece episodes 326-746, which cover Thriller Bark, Summit War (Sabaody Archipelago, Amazon Lily, Impel Down & Marineford), Fishman Island, Punk Hazard, and Dressrosa story arcs.
However, this update does not cover the rest of the series, so there won’t be access to Zou, Whole Cake Island and Reverie story arcs as well as any filler content in-between just yet. The specials as well as the “Special Edition HD episodes” of the earlier arcs are also not mentioned in this batch.
Outside of the UK, Ireland and Nordic territories; French, German, Russian, Italian and Spanish-speaking Europe, and Portugal territories will also be able to access more subtitled episodes of the series.
“Monkey. D. Luffy refuses to let anyone or anything stand in the way of his quest to become the king of all pirates. With a course charted for the treacherous waters of the Grand Line and beyond, this is one captain who’ll never give up until he’s claimed the greatest treasure on Earth: the Legendary One Piece!”
Plot Synopsis via Crunchyroll
Outside of streaming, One Piece is licensed by Funimation UK for the United Kingdom and Ireland for home video release. At the time of this post, they have released DVD collections 1 to 23 (episodes 1-563). The distributor has also released the One Piece films from the first film all the way to Strong World, Film Z and Stampede.