To claim (taken from website):
You will need to register with redspottedhanky.com to be able to claim your voucher, Click here to register .
If you are a new user, complete the registration form with your details. If you are an existing user, log into your account and click on ‘Personal Details’. Enter the code ‘SunNorthWest’ in the Sun Voucher Offer box.
We will send you a confirmation email to confirm when your voucher will be available in your redspottedhanky online account. Please note, vouchers can take up to 72 hours to be added to the created account.
This offer is valid for new AND existing redspottedhanky customers and is non-transferable. Only one voucher per person. Registrations can take place up until 16th May, 2012. For full terms and conditions, visit redspottedhanky.com/thesun.
So grab it whilst you can! Trains are so overpriced so it's a great offer. I think a day trip somewhere is needed!