Fantasy/English Folklore

I'm looking for any interesting novels mixing a high level of english folklore with fantasy.

How about Jonathan Strange & Mr Norrell by Susanna Clarke?

A less challenging (but also excellent) read is Elizabeth Marie Pope's The Perilous Gard.

The Dark is Rising. Not so much the first book, which was written without the series in mind, but the rest of series draws heavily on both Arthurian and other British folklore. It's one of my personal favourites.

3:

The Dark is Rising sequence is indeed awesome, the movie was a travesty.

A bunch to get you going:

The Promethean Age series by Elizabeth Bear (start with Blood and Iron); Snow White and Rose Red by Patricia Wrede; Midnight Never Come by Marie Brennan; Tamsin by Peter S. Beagle; and Singer of Souls by Adam Stemple

I might add I'm generally not a big fan of Fae/Faery as it's been terribly overused across the years.

Gene Wolfe's Castleview, subtitled "An Arthurian Epic of Modern Illinois," describes an intrusion of various folkloric characters into the life of an automobile dealer.

4> shhh. There is no movie.

Mists of Avalon by Marion Zimmer Bradley

Check out the Pendragon Cycle, including Taliesin by Stephen R. Lawhead

Not fantasy, but Jennifer Roberson is known for fantasy, and she wrote Lady of the Glen which is a retelling of Robin Hood.

Also the Keltiad series, by Kinnealy - forget the full author name.

Ah, also, Thomas the Rhymer by Ellen Kushner

Alan Garner's books: The Weirdstone of Brisingamen, Moon of Gomrath, Elidor and The Owl Service all have a folklore background. Welsh, mostly.

Tam Lin by Pamela Dean might interest you. I thought it was rather uneven and too long but have friends whose taste I generally respect who absolutely adore it.

Don't forget the classics.

The Once and Future King.

The age of Misrule and
Hobberdy Dick

Are very different and both good in their way.

9>the Keltiad series is by Patricia Kennealy, sometimes writing as Patricia Kennealy Morrison

There's the Prydain Chronicles beginning with The Book of Three, but then I suppose that's based on Welsh legends rather than strictly English.

the Garner novels are more English than Welsh apart from the owl service.
think my two offerings are nearest the mark though

The Garner novels are more English than Welsh apart from the owl service.
think my two offerings are nearest the mark though Katherine M Briggs is a noted british fooklorist

Robin McKinley does retellings of fairytales.

Lloyd Alexander's 'Chronicles of Prydain' have a Welsh leaning.

George MacDonald, The Princess and Curdie and The Princess and the Goblin.

Puck of Pook's Hill by Rudyard Kipling is a children's classic, well worth reading. It brings in most of the classic English folklore.