There a lot of movie subscription services available in the UK, I am signed up to two of them, but there are plenty of movies available to stream free of charge. The BBC selection even includes a Hitchcock film, meaning it has one more than Netflix! Here are a few recommendations:
BBC iPlayer
There are some excellent movies available on the BBC streaming service including 23 RKO movies. Here are a few I would recommend:
Spotlight (2015) – The best picture Oscar winner from 2016 tells the true story a Boston Globe report that uncovered the scandal of child molestation and cover-up within the Catholic Church.
Election (1999) – Quirky comedy from Alexander Payne. Matthew Broderick plays a teacher whose life spirals out of control when he goes against overachieving student Reese Witherspoon.
The Company You Keep (2012) – Thriller directed by and starring Robert Redford. A thriller of the type they don’t really make these days, probably why it went under the radar on release in 2012.
The Elephant Man (1980) – Atmospheric and beautifully shot true story of John Merrick. David Lynch’s second feature.
Bringing Up Baby (1938) – Howard Hawks’ delightful Screwball comedy with Katharine Hepburn, Cary Grant, and a leopard!
Citizen Kane (1941) – The best film of all time is a hard burden for a movie to carry; in recent years it has been fashionable to push back against this and claim to not like the film. Don’t believe the detractors, Orson Welles’ masterpiece may not be the best film ever made, but it is still fantastic.
The Magnificent Ambersons (1942) – Alternatively, take a look Welles at his follow up. Butchered by the studio, it isn’t exactly the movie he intended, but is still fantastic.
King Kong (1933) – Forget the Peter Jackson version, or the recent Skull Island, the original 1933 is the true King of the monsters! stop motion animation was as groundbreaking in its day as modern CGI is now, and Fay Wray is fantastic in the lead.
Suspicion (1941) – Joan Fontaine plays a shy young heiress, Cary Grant the charming but penniless playboy she falls for, and marries. He may or may not be planning to kill her for her money. Fontaine won the Best Actress Oscar, the only acting Oscar in a Hitchcock film.
Fort Apache (1948) and She Wore a Yellow Ribbon (1949) – The first two of John Ford’s cavalry trilogy. What more do I need to say. Watch them!
Cat People (1942) and The Curse of the Cat People (1944) – Low budget horror classic from legendry producer Val Lewton, and director Jacques Tourneur. The influential movie is a perfect example of less is more in the genre. The sequel came just two years later and is also excellent.
I Walked With a Zombie (1943) – Atmospheric zombie movie, also from director Jacques Tourneur. More disturbing than scary, its masterpiece of the genre.
All 4 
The streaming service for all Channel 4, including Film 4 also has a large selection of movies, here are my picks:
Sweet Sixteen (2002) – Ken Loach movie about a teenager determined to raise enough money to get a home for himself and his mother who soon to be released from prison. The film stars Martin Compston in his first acting role. Having recently signed for the Scottish second division side Greenock Morton, he was more interested in a career in football than acting.
The Warrior (2001) – Asif Kapadia doesn’t just make documentaries. The Warrior stars Irrfan Khan (who recently passed away) as a warrior in feudal Rajasthan attempting to give up the sword. Shot in the Himalayas and the deserts of Rajasthan the film looks stunning. It won the Alexander Korda and Carl Foreman BAFTA’s.
Slow West (2015) – Revisionist Western, and directorial début from John Maclean, previously best known as keyboard player/DJ and founder member of The Beta Band. A strange mix of tone, it is often violent, but also very funny, while still remaining at its heart a western.
Slumdog Millionaire (2008) – Danny Boyle’s Best Picture winner launched the career of Dev Patel. As a teenager is accused of cheating on the Indian version of “Who Wants to be a Millionaire?” we see flashbacks of his extraordinary young life.
Tangerine (2015) – I haven’t actually seen this film, but it comes highly recommended; director Sean Baker’s next film The Florida Project was excellent. Shot entirely on an iPhone.
Rakuten TV 
The VOD site has a small number of movies that are free to stream, my pick of them are:
The Ninth Gate (1999) – Curio from Roman Polanski that takes him back to the demonic supernatural of his earlier career. Johnny Depp is perfectly cast.
The Crazies (2010) – Remake of the George A. Romero classic from 1973. It isn’t a masterpiece, but it’s a good fun horror. Radha Mitchell and Timothy Olyphant are always worth watching.
My 5 
Chanel 5’s streaming service also has a reasonable selection of movies, here are few recommendations:
Bad Lieutenant (1992) – Abel Ferrara’s story of a detective on a downward spiral of drink, drugs, prostitutes and gambling, but there is a faint hope of salvation and redemption in his latest case. Harvey Keitel is truly outstanding in the lead role.
Cold In July (2014) – Revenge thriller from director Nick Damici and his long-term writing partner Jim Mickle. The plot has enough twists and turns to hold the interest. The cast is excellent particularly Sam Shepard.
Triangle (2009) – Time loop horror thriller. A low budget masterpiece from writer/director Christopher Smith. The success of the film rests on the excellent performance from Melissa George.
eXistenZ (1999) – One of David Cronenberg’s most David Cronenberg movie! The plot keeps you guessing all the way, and Jennifer Jason Leigh is brilliant.
Camp X-Ray (2014) – Kristen Stewart is fantastic in her first movie after the final twilight film. Stewart plays a young inexperienced guard at Camp X-Ray at the Guantanamo Bay eight years after 9-11. The theme of the film is exactly what you would expect, but it is a lot more subtle and nuanced than you would expect.
ITV Hub
only has The Equalizer and a couple of Carry On movies available at the moment.
I Hope there is something here of interest!