RedSpottedHankey must really want you to book with them. They’re giving out 20,000 £5 vouchers when you buy something at WH Smiths. However the code is apparently the same on each voucher so all you need to do is go here and enter VOU172RGSDHK. The store shouldn’t matter so just put your local one.
They say it’ll take 96 hours for this code to be validated, then they should email you a £5 code within two working days.
When you enter this code on the RedSpottedHankey page, make sure it’s in the validation code section of your personal details, not the voucher code tab. The voucher should appear in the voucher code section within a few days to redeem against any train travel in the UK by 31st May 2014.