Embassy legalisation for use in Slovenia
This service does not apply to Slovenia. A single British certification finishes a paper leaving Glasgow, and nothing behind it adds a further mark. Anyone arranging embassy legalization for Slovenia from Glasgow through a consulate is booking a stage this destination does not run, and there is no address in the city that could host such a stage.
The counter and the post box
The two offices on this route do different jobs and behave in different ways. Glasgow Registration Office at 45 John Street, Glasgow G1 1JE is somewhere you walk into, where a certified extract of a Scottish birth, marriage or death entry is printed for you while the sheet at home stays exactly where it is.
The Legalisation Office (FCDO) is not a place in that sense at all. It works from a post box, deals with the public by post rather than across a counter, and sees your paper without ever seeing you. Everything it settles, it settles from what is inside the envelope.
The Glasgow → Slovenia route step by step
Get the right version of the paper, then send it onward. That is the whole order of work, and the two acts happen in two different cities. Embassy attestation for Slovenia would have added a third act behind them, and it is simply not there. Nothing runs alongside anything else and nothing can be pulled forward, because the desk cannot begin on a sheet that has not reached it yet.
Cost & timing for this route
An official fee applies to each document the certifying desk handles, and it is the only charge on the run. Standard work is quoted at 7–10 business days and express work at 2–3 business days. Both belong to that desk, so the two postal legs and your own trip to the counter sit outside them.
What the destination expects
A properly issued paper, marked once, and nothing beyond that. Because the second place never meets you, anything you might have explained in person has to be plain on the sheet itself. That is the practical reason to order a fresh certified copy rather than send something old and creased, and to keep the original at home.