Hi, I have built many scale biplanes and the older ww1 era ones that have cable bracing wires I have found that nylon coated braided fishing line is tha best choice. It is inexpensive, readily available and the sleeves to crimp the wires together are also easily found. Fot the 30s era, I am not shure what was used on the later model Tiger Moths, I have used silver vinyl lacing for the streamlined bracing wires used in that era. The results were OK. I have attached a pic of a kit bashed GP P6E using the vinyl streamlined bracing wires. They are more work to install than the braided cable and add little, if any, structural strength.
Good Luck, Jack