The given coords are for a handy rail station. The cache isn't there.
The first task
Where is she pulling up? That's the password to the Night Mail page. The username is nightmail. Use lower case throughout.
The second task
You are in control of the Night Mail. You need the name of the first Pullman, and of the second Pullman. Use all lower case. That's the username and password to this page
The third task
This is a night cache. I'd recommend using a head torch to see where you're going, a really strong torch to find the next fire tack, and a stick to keep your balance on the paths. Follow the trail of fire tacks.