What each stamp in the Qatar chain means
It helps to know that no desk in this chain reads your document. A notary confirms whose signature is on the page. The FCDO Legalisation Office confirms that the notary sits on its register. The Embassy of the State of Qatar (Consular Section) then confirms the British mark it already recognises. Each desk vouches for the one before it, which is what holds the sequence together.
That is also why a stage cannot be skipped or swapped around. A consular officer in London has no way to know a Scottish registrar's signature on sight, but does know the government mark laid over it. Embassy attestation for Qatar is the last link in that line, and it only works when the earlier links are already on the page.
The Scottish side of the file
Scotland runs its own civil register, so an Edinburgh birth or marriage entry is ordered from Edinburgh Registration Service at City Chambers, 253 High Street, Edinburgh EH1 1YP. It prints certified extracts, which are full copies of the register entry rather than photocopies of the certificate you hold. That difference is what lets the extract carry a live signature into the chain.
Degrees, company papers and police records begin elsewhere, but the idea holds: put a certified copy in the post and keep the paper you cannot replace at home. Nothing about embassy legalization for Qatar from Edinburgh asks you to travel, because the FCDO Legalisation Office works entirely by post out of Milton Keynes and the consular stage is handled for you.
Cost, timing and the Doha end
Budget about £45 for the FCDO stage and a consular fee on top, set by the Consular Section rather than by any British office. The British stage runs 7–10 business days as standard and 2–3 business days on the express route. The consular stage adds its own wait, and it is usually the part that decides when the file lands in Doha.
Most people who legalize documents for Qatar are building a work or family file: a degree for a residence permit, a marriage entry for a family visa, a police record for a Doha employer. Employers there tend to want the whole set stamped at once, so gathering every paper before the chain starts saves paying for a second run through it.