Edible Landscapes in Finsbury Park have a ready supply of wood chip courtesy of the park gardeners. A very useful resource for covering the paths and mulching the beds. I did some shovelling and borrowing when I visited the garden on Tuesday.
As a rule of thumb any soil is improved by adding organic matter. In fact some plants thrive on nutrient poor soil but in general mulching is all to the good. At this time of year a layer of wood chip adds to nature's mulch i.e. fallen leaves.