So today - I took out the broken zip, put in a new zip, sewed two side seams, found the already interfaced facings, sewed them onto the waist and ..............viola!
This took me all of one and a half hours! I still need to do the hem, but I will let the bias drop a little. Actually I will let it drop for a few days as I need to go up to Shepparton to attend to family stuff. Happy sewing :)