Hardening fix would be the last fix I would use. You might try resoaking the print in a non-hardening fix before trying to tone Ilford paper. The cold tone papers from Ilford don't seem to respond to selenium like the warmtone papers do. This is just my observance though and I would not try to defend this statement. You might buy some Kodak Rapid Fix and mix your own and leave out the part B. That will make a non-hardening fix that you can carry to school and use for your own use.