I'm in the US and wanted to purchase my rail tickets as soon as the dates become available (4 months prior). However, they don't mail the passes outside the UK. Will I still be able to purchase the rail tickets with the discount without having the Two Together Pass in hand? Or am I S.O.L.?
Yes pre purchase online and select you do have the pass in the drop down menu.
Then once in UK and Before using any of the discounted tickets,head to a staffed desk and they will issue it to you.
You must have the pass with the tickets when you travel,or at best you will have to pay the balance, at worse entirely new tickets