Hmmm ... Apart from mate we'd use ... *thinks* dude? Man? It is very Americanised nowadays. We use 'bloke' too. But 'Mate' is by far the most popular.
As for trains, I am pretty sure there's not one direct to the Scottish Highlands ... or at least not one on a regular basis. You can get one from London's Kings X that takes you up to Glasgow through the GNER East Coast Mainline ... some may terminate at Newcastle or Edinbrugh, so you'll have to transfer to Glasgow and from there find the local regional train station you want to use. The GNER website (www.gnertickets.co.uk) is very useful. Just key in the information.
Note: trains are very unreliable and often get stopped mid-course. So if you want an authentic story, have your character stuck at York/Darlington/Newcastle/Doncaster for an hour in the freezing cold.
The doors are usually automatic. I was an old GNER train the other day that still used the 'stick your hand out the window and pull the lever' technique, but they're a minority. There's lots of different train companies, don't forget, too. I have only mentioned GNER because I know it has trains going straight up the middle of England and into Scotland.