You can browse the books from the British Isles by using the Author-Title List below (updated August 14 2016) or by browsing the British-Celtic label. For random browsing, try the Library Randomizer: British-Celtic. And you can also use Diigo to browse the English and Celtic books by category:

Barham. Legend Land - Cornwall and Wales
Barham. Legend Land - Devon and Cornwall
Belloc. Moral Alphabet
Boothby. Fables and Satires
Bray. A Peep at the Pixies
Brooke. Golden Goose Book
Brooks. Wonder Stories from the Mabinogion
Bulfinch. Age of Chivalry
Campbell. Popular Tales of the West Highlands
Campbell. The Celtic Dragon Myth
Carroll. Alice's Adventures in Wonderland
Carroll. Through the Looking Glass
Child. English and Scottish Popular Ballads
Clay. King Arthur and His Round Table
Creswick. Robin Hood
Croker. Fairy Legends of Ireland
Crossing. Tales of the Dartmoor Pixies
Curtin: Myths and Folk Lore of Ireland
Denslow. Mother Goose
Dickens. A Christmas Carol
Douglas. Scottish Fairy and Folk Tales
Dunn. Tain Bo Cualnge
Dyer. Folklore of Shakespeare
Edwards. The Book of Old English Ballads
Emerson. Welsh Fairy Tales
Faraday. The Cattle-Raid of Cualnge
Graves-Denham. The Irish Fairy Book
Gregor. Folk-Lore of the North-East of Scotland
Gregory. A Book of Saints and Wonders
Gregory. Cuchulain of Muirthemne
Gregory. The Tuatha De Danaan
Grierson. The Scottish Fairy Book
Griffis. Welsh Fairy Tales
Guest. The Mabinogion
Hartland. English Fairy and Other Folk Tales
Higginson. Tales of the Enchanted Islands
Hull. The Boys' Cuchulain
Hyde. Irish Gaelic Folk Stories
Jacobs. Celtic Fairy Tales
Jacobs. English Fairy Tales
Jacobs. More Celtic Fairy Tales
Jacobs. More English Fairy Tales
Kennedy. Legendary Fictions of the Irish Celts
Kline. Beowulf
Kline. Chaucer's Canterbury Tales
Lamb. Tales from Shakespeare
Lang, Andrew. Ballads
Lang, John. Gulliver's Travels
Lang. King Arthur
Lang. The Nursery Rhyme Book
Leahy. Heroic Romances of Ireland
MacCulloch. The Religion of the Ancient Celts
MacGregor. Stories From the Ballads
Macgregor. Stories of King Arthur's Knights
Mackenzie. Elves and Heroes
Mackenzie. Wonder Tales from Scottish Myth
Macleod. Stories from the Faerie Queene
MacManus. Donegal Fairy Stories
MacManus. Merry Tales of Irish Folklore
Macpherson. The Poems of Ossian
Mandeville. Aesop Dress'd.
Marshall, Henrietta. Stories of Beowulf.
Marshall. Stories of Guy of Warwick
Masson. Folk Tales of Brittany
Meyer. The Voyage of Bran
Moore. The Folklore of the Isle of Man
Morris, Charles. Tales of King Arthur (1)
Morris, Charles. Tales of King Arthur (2)
Morris, Williiam. The Tale of Beowulf
Nesbit. Beautiful Stories from Shakespeare
Nichols. Old Ballads - Volume 1
Nichols. Old Ballads - Volume 2
Nichols. Old Ballads - Volume 3
Nichols. Old Ballads - Volume 4
O'Donoghue. Brendan the Voyager
Painter. Palace of Pleasure, 1
Painter. Palace of Pleasure, 2
Painter. Palace of Pleasure, 3
Pyle, Howard. Champions of the Round Table
Pyle, Howard. Merry Adventures of Robin Hood
Pyle, Howard. Sir Launcelot and His Companions
Rackham. Mother Goose
Rhys. Celtic Folklore: Welsh And Manx
Riggs. Beowulf
Rolleston. Myths & Legends of the Celtic Race
Rolleston. The High Deeds of Finn
Seymour-Neligan. True Irish Ghost Stories
Sidgwick. Ballads of Robin Hood
Sikes. British Goblins - Welsh Folklore
Spence. Legends and Romances of Brittany
Squire. Celtic Myth and Legend, Poetry and Romance
Steel. English Fairy Tales
Stephens. Irish Fairy Tales
Tappan. Chaucer Story Book
Thomas. The Welsh Fairy Book
Twain. A Connecticut Yankee in King Arthur's Court
Warren. King Arthur and His Knights
Wilde. Ancient Legends of Ireland
Wilde. House Of Pomegranates
Wilde. The Happy Prince and Other Tales
Wright. Brandan: A Medieval Legend of the Sea
Wright. The Real Mother Goose
Yeats. Fairy and Folk Tales of the Irish Peasantry
Yeats. The Celtic Twilight
Young. Celtic Wonder Tales