Jock, I would NOT recommend using your phone. When the iPad backdoor was discovered yesterday, I borrowed a colleagues iPhone 6 to check it out. The experience was pretty much awful on that little device. Very very slow to load the graphics and I'd be worried about being able to make your selections in time.
A full iPad may work better, but I'd recommend using a normal computer to do this. If you have firewall or other concerns about functionality at work, I still wouldn't count on your phone as your backup. JMO