With the trees now virtually free of foliage this time of year is excellent for firstly locating Treecreepers and secondly photographing them.
Apart from hearing their high pitched contact calls I find that the best way of finding them in mature woodland is to stand in a position where you can see twenty of thirty well separated trees with exposed trunks particularly at their base.
Generally Treecreepers will fly down to the base of a tree to start their corkscrewing ascent, in flight their white underparts show very well and its relatively easy to pick them up as they flit from tree to tree.