This novel in the New Adventures of Doctor Who series is in fact downloadable from the BBC website
here in various formats, with added comments by Mark Gatiss from 2006 (after his TV stories The Unquiet Dead and The Idiot's Lantern had been broadcast).
The setting is a familiar Whovian one (most recently seen in The Eleventh Hour): rural England, alien menace, the Doctor sorts it out. To be specific, we're in a Yorkshire village in December 1968; Gatiss packs in a lot of detail, including some memorable characters - the staff of the local radio observatory; the young man who develops a relationship with Ace; the elderly actor who used to play Professor Nightshade on telly (a mixture between Quatermass and the First Doctor). Gatiss says in the notes that he was trying to write a Who book that really belonged more in the horror genre; it works for me.
The next New Adventure in sequence is
Paul Cornell's Love and War, which I read a year and a half ago (and greatly enjoyed); but I shall skip it for now and go on to Ben Aaronovitch's Transit - I am not a particular fan of Aaronovitch's writing, but let's see if this will bring me round.