As of when I post this, there is slightly less than 24 hours in which to nominate the best UK sf of 2012 for the BSFA Awards.
Works nominated thus far are listed here, but don’t let that limit your suggestions. Equally, don’t assume that a book already nominated will necessarily have enough nominations to make the shortlists without your contribution. Only BSFA members can nominate, but this year’s Eastercon attendees will be able to vote as well on which piece will win each of the four awards from the most-nominated works.
P.S. I note that thus far, only four novels by women have been nominated for best novel of 2012, as opposed to 34 by men. I suspect this is the aftermath of the paucity of contracts held by UK women sf authors a couple of a years ago; but that doesn’t mean the current nominations exhaust works worth considering for nomination.
vector-bsfa.com 
Despite the name of the award, it does formally include works of fantasy, so Frances Hardinge’s A Face Like Glass (for instance) is eligible for nomination.
Well, I put in a nomination for J.T. Colgan’s “Dark Horizons” (the author being better known as Jenny Colgan). Though as it is a Doctor Who novel, I suspect it may not make the cutoff.
Didn’t Angry Robot bring out a bunch of books by women last year? Madeleine Ashby etc?