It's really easy to get to Glasgow or Edinburgh from Leeds, and you can get a cheap return train ticket on The Trainline
Put in your desired departure and return date, get the times and prices, then look for the link at the bottom that says something like "it might be cheaper to buy two singles" - it usually is
As for a tour guide? Do you need one? How long will you be going for? What are your interests? When you arrive in Edinburgh, you are right at Edinburgh Castle
You can't miss it!
I'm originally from Scotland, but have been living in Ireland for a year - I actually have a half-Irish/half-Malaysian friend here, that I was touring with today funnily enough
If I can be of any help, let me know