Don't sew it on as you may want to replace it later which means unpicking the stitches. If I were you I would nip down the local DIY store and get some double sided sticky tape. Stick one side to the back of the badge, then position your badge on your shirt pocket. Once you do get a County badge, then think about having that sewn on. Alternatively if you but a new kit, have the County badge embroidered on to the shirt.