Question: Apologies from a QGIS beginner but I have added a WMS layer of polygons to fill in the gaps of an existing data set I have. the problem is that I want all of this data to have the same style (colour etc) and the WMS layer which comes up as orange cross hatching doesn't seeem to be able to be modified to a single colour for example. Is it actually possible to change the style of a WMS layer in a way that is possible for beginners?

Answer: 
No. WMS is a image that is generated and sent from a server. Once you have it in QGIS it's too late to change it.
Yes, if you use GeoServer with [Dynamic Colormap Generation](http://docs.geoserver.org/stable/en/user/community/colormap/index.html).