This is going to kill my cut and paste abilities, and I'm only listing the ones I quickly see on my f-list of whom many are UK writers; there are dozens of others. If you go to kaz_mahoney's LJ you'll find loads of novelists on her profile, also probably on Jo Knowles because she runs a famous Young Adult writing activity every autumn.

Sorry, I ran out of tag-fu...

aliettedb Aliette de Bodard
allanstratton YA author Allan Stratton
amygreenfield Amy Greenfield
anghara Alma Dromic
autopope Charles Stross
beth_bernobich Beth Bernobich
brownnicky NM Browne
carriejones Carrie Jones
coebooth Coe Booth
dancinghorse Judith Tarr
desperance Chaz Brenchley, Daniel Fox & various other names
fastfwd Pat Cadigan
fredawrites Freda Warrington
ianmcdonald Ian McDonald
janetedwards Janet Edwards
jbknowles Jo Knowles
jemck Juliet McKenna
jenreese Jenn Reese
jer_bear711 Jeri Smith-Ready
jessica_shea Jessica Shea
jimhines Jim Hines
justinar Justina Robson
karenhealey Karen Healey
kateelliott Kate Elliott
kaz_mahoney Karen Mahoney
la_marquise_de Kari Sperring
lindanagata Linda Nagata
lyda222 Lyda Morehouse + Tate Halloway
m_steifvater Maggie Stiefvater
maeve_the_red Jaine Fenn
marthawells Martha Wells
matociquala Elizabeth Bear
mdep Marianne de Pierres + pseudonyms
merriehaskell Merrie Haskell
mevennen Liz Williams
moschus Justine Musk
msagara Michelle Sagara
nisi_la Nisi Shawl
nojojojo NK Jemisin
ogresan Richard Parks
saladinahmed Saladin Ahmed
sarah_prineas Sarah Prineas
seanan_mcguire Seanan McGuire
sheela_chari Sheela Chari
shweta_narayan Shweta Narayan
splinister Maura McHugh
stephanieburgis Stephanie Burgis
stillsostrange Amanda Downing
stina_leicht Stina Leicht
suzannemcleod Suzanne McLeod
tltrent Tiffany Trent
yuki_onna Cat Valente