I also can't find where abouts the promo code box is either :S
No it isn't.
This offer is only valid Merlin pass holders
Still works, booked a room for July B&B for a total £215 for 2 nights at enchanted village for the family. Not bad at just over £100 per night.
using the "Get Link" button at the top of this page should take you to the Alton towers website, displaying "up to 40% off" and The Sun logo. Just below that you should have a Promotion code box, enter 'SUNHOT' there.