I'd go along with the recommendation made by Ld. Dietrich von Greyssen. You have within the SCA a thousand years of Scottish History to choose from, - if that is the culture which is your primary interest at the moment. The Culture of the geographic area which eveolved into Scotland changed a great deal in that time.
So I respectfully suggest that you first of all plan for simple garb so that you can attend events, - without making a major outlay of time and perhaps money acquiring equipment/clothing you may later wish to change.
Now, Scotland being your primary interest, may I respectfully suggest that you contact the Seneschal of the Shire of Harpelstane, [centred in and around Edinburgh.
Since their Populace are "on-the-spot" and undoubtedly have members who have had the luxury of doing "on-the-spot" research into Scottish history, I cannot think of any on the planet in a better position to help you with references to books and online resources; maybe even sharing their own researches with you - to help you to firm-up your wish to assume a persona from pre-1600 Scotland.
Their Seneschal is Lord Torkil Mor, and his e-mail address is <seneschal@...
In humble service,
Lord Matthew Baker