One of The National Archives' most recent blog posts is all about advertisements. If you're not already streaming these, I'd recommend them - there have been some fascinating talks lately.
This one is called 'The huns have got my gramophone: advertisements from the Great War' and is given by Amanda-Jane Doran and Andrew McCarthy who produced a book of the same name. I've checked, and you can borrow it from the First Floor of the Millennium Library (or reserve it online and pick it up at your local Norfolk library).
If you're interested in local advertising for this time period, head to Norfolk Heritage Centre to look at newspapers, trade directories, Carrow Works magazine, posters in the ephemera collections and much more.
Picture Norfolk is busily digitising First World War posters, and you can see examples of the new material on Norfolk's First World War blog or by following @picturenorfolk and @norfolkinww1 on twitter.