How many miles? How long does it take? Cost??
Looks like 8 hours on the train you can book it online
Highland Rail Rover ticket may well be of interest to you
How can I get from the Edinburgh Airport to the train station that goes to Thurso? I'll be traveling with a child.
Tram to Haymarket.
If you can, take drinks and food (sandwiches, chips, fruit) with you . The ride is long. The cars are small. Scenery is great. However, a child will probably tire of seeing mountains and more mountains, so bring something for him/her to do .