Alan Partridge is back, and this time he’s restoring a lighthouse. The third volume of the Norfolk microstar’s faux autobiography is a meticulous parody of the celebrity-in-search-of-a-televisable gimmick genre, blending fan-friendly, behind-the-scenes tales of his more recent public adventures (This Time, Scissored Isle, From the Oasthouse) with a classic midlife lurch for purpose, part Griff