You may be aware that an increasing number of legal  anime streaming websites are being launched. For the US there are Crunchyroll, Anime Network,  Anime News Network, Viz Video, Funimation, Toonzaki, YouTube, Nozomi, and probably others I’ve missed.
UK anime fans get a poor deal, as most of the streaming sites are restricted to the US, and even the ones that work block many shows for UK viewers. I’ve found only three worthy of serious consideration in that they allow UK viewing, they have a good range of shows, and they technically work properly (on Broadband).
UK: Crunchyroll: many shows, including several of latest Japanese season, free with adverts (with £ ad-free premium option), works well.
UK: Anime Network: useful number of older shows, but you have to find UK-enabled by trial and error. $4.95 per month, works well but may not expand to full-screen. 1st episodes are generally free.
UK: YouTube: used as a delivery network by several distributors e.g. Nozomi. Select: TV shows, Comics and Animation, Anime. Free, can work well but may stutter, delivery may be low-resolution 360p.
A Â useful reference is here. In addition there are large numbers of sites that promise free streaming of thousands of anime, but when you try them may not work well, or at all, and then you may find your computer is infected with some malware 🙁