If, let's say, I want to go from London to Edinburgh with a point to point ticket:
1) If I buy a ticket between those two cities, could I then make a stopover in say Newcastle for a few hours on that ticket without incurring any other charges, or would I have to buy two separate tickets London-Newcastle and Newcastle-Edinburgh? (And what about reservations on two different trains?)
2) If the answer to the above is only one ticket, what happens if I want to stay overnight in Newcastle? Still one ticket or now I need two tickets?
Thank you in advance.