Can I buy a ticket for someone else?
Yes. Train tickets can be used by anyone. The only exception is Self-Print tickets, because these have the name of the traveller printed on them and the traveller has to show some ID on board to validate the ticket. You'll still be able to buy them tickets through Self-Print, all you have to do is book in their name and tell them they'll need to bring some ID.
If that person is collecting tickets from a ticket vending machine, they will need the credit or debit card used to make the booking. This might be a little tricky to work around so bear this in mind when booking. If it helps, you can request that tickets are posted to any UK postal address when you book online.
You can also create Gift e-Vouchers for someone to purchase a train ticket on lner.co.uk. You can find out more about Gift e-Vouchers here.