If you are a UK person, this is the recommended trains to take...
The ones that will get you there and back for cheap.

These seats are flying out the door.
Book fast... this week in fact.
If you want to stay overnight, you HAVE to stay two nights. All the trains on the 3rd are booked. Use this plan:
-------------------
http://www.eurostar.com/UK/uk/leisure/late...ls/youth__1.jspGo there, clock book now, and fill out the booking as it appears on my screenshot.
Um, I'm deadly serious in saying the following.
I have a room booked here:
http://images.hostelworld.com/images/hostels/7810_4.jpgThere's enough room for like 2 people to sleep on the floor if they bring a sleeping bag or something, and a pillow in a backpack.
As long as you come in individually, they won't get suspicious.

Dhboy123 is already sleeping on the floor. I MIGHT be able to squeeze one more in.
This option is for those that want to stay the two nights.
If you're staying overnight, expect to go clubbing if you can.
If we're caught, be prepared to pretend to be gay.
If you want to stay overnight, that place has some dorms for 20 pounds per night. You share with 3 other people in the one room though... Steve is doing that. You could probably request a room with him so you're not so lonely
Need more details?
Post here.
*NOTE: The English tubes and train stations open at 5:25 AM, you may need to sort out other ways of getting to the station. ~ Cam