From the website:
How it works:
All orders placed with Forge World between 00:01 (GMT) Friday 31st October 2014 and 23:59 (GMT) Wednesday 31st December 2014 will receive a free Standard Shipping voucher.
Free Standard Shipping vouchers must be redeemed before 17:00 (GMT) Saturday 31st January 2015. There is no limit to the number of vouchers you can collect or use.
To redeem your voucher, please call the Forge World Customer Services team on 0115 9004995 (UK), 011 44 115 9004995 (US & Canada) or 0044 115 9004995 (Europe and Rest of the World).
Alternatively, if you are unable to ring you can download a Free Standard Shipping Fax Order Form by clicking here, then fax your order to us on 0115 9004882 (UK), 011 44 115 900 4882 (US & Canada) or 0044 115 900 4882 (Europe and Rest of the World)
When you call, please have your voucher number and the number of the order with which you received your voucher to hand – you will need both of these to take advantage of the offer.