Instructions:Spotted this affiliate deal on the 4g.co.uk website. T&C's here: https://voucherwindow.com/645
Codes and T&C link:
Nano SIM – Enter Code IPHONE50 here https://voucherwindow.com/641
Combi SIM*– Enter Code HANDSET50 here https://voucherwindow.com/645
You can also get up to £50 Quidco cashback as an alternative: http://www.quidco.com/ee-mobile-contracts/?ac
Unsure if these deals could be combined for a £100 saving.