Haven’t looked at the other responses yet, so sorry if I stole anybody’s stuff : )
Sense and Sensibility (the one with Emma Thompson and Hugh Grant)
A Hard Day’s Night (The Beatle’s first movie)
Bleak House (actually a miniseries, the one with Gillian Andersen)
Ghandi
The Elephant Man
The Barchester Chronicles (also a miniseries, with a young Alan Rickman as a hot, sexy but unctuous minister called Obadiah Slope, some have said that J.K. Rowlings saw this and used his character for part of the personality for Severus Snape)
Cranford (also a miniseries with Judy Densch)
All Creatures Great and Small (also a miniseries)
Goodnight Mr. Tom (a heart-wrenching tale of an old British bachelor curmudgeon and what happens when he is “forced” to take in an orphan boy during WWII)
Becoming Jane (Anne Hathaway and James McAvoy, swoooooon)
Mrs. Brown
Mrs. Henderson Presents (Bob Hoskins full frontal!)
Is Anybody There? (Michael Caine at his best in this loving, heartbreaking story)
Educating Rita
Monty Python and the Holy Grail
To Sir With Love
The Lion in Winter
Venus
Dracula (the one with Frank Langella, although he’s not British, the rest of the cast, including Donald Pleasance and Laurence Olivier are)
Star Wars Episode IV (mostly British made)
Harry Potter and the Deathly Hallows part 2 (this is my favorite in the series, but I love them all)
Love Actually
Bridget Jone’s Diary
Peter Pan (the live action version from 2003 with Rachel Hurd-Wood as Wendy)
The Piano
The Young Sherlock Holmes (with Nicolas Rowe as Sherlock)
A Christmas Carol (the one with Patrick Stewart)
The Little Princess (even though Shirley Temple wasn’t British, the other actors were and it’s set in England)
Oliver Twist (from 2005 with Ben Kingsley as Fagin)
Wind in the Willows (the live-action version from 2006 with Matt Lucas as Toad)
Jane Eyre (the one from 1996 with Anna Paquin as the young Jane)
The Winter Guest (starring Emma Thompson’s mother Phyllida law, and written and directed by Alan Rickman)
Victor Victoria (from 1995 with Julie Andrews)
The Sound of Music (mostly British cast)
Mary Poppins
The Girl with the Dragon Tatoo (loved both versions, I think I liked the British one just slightly better than the original because of the more lush, freezing cold-feeling scenery)
The Pink Panther Strikes Again (my favorite of the Inspector Clousea/Peter Sellers series)