My daughter pre-booked a train ticket (with student railcard and booked seat) for Saturday about 1pm, travelling down from York to Ashford International, Kent via Kings Cross/St Pancras. She is now travelling on Thursday, so doesn't need the Saturday ticket.
If you want to travel to London (or even Ashford) then and have a rail card but no ticket, it will cost you about £50-60 on the internet. Hers cost her £19, so you could save yourself £30-40+. If it is of any use to you, you'll have to get it today.
Anyone interested, give us a shout.
... and the ones that won't