Embassy legalisation for use in Myanmar
Myanmar wants its own mark on a British paper before its offices will act on it. That is the plain shape of the job, and it is why people who legalize documents for Myanmar cannot stop once the British certificate is on the sheet. The final stamp is the one a Myanmar office reads; everything before it exists to make that stamp possible.
The awkward part is the return leg. A file bound for embassy attestation for Myanmar makes several journeys before it is finished, and every one of them is postal. Building those trips into your plan is more useful than chasing any single desk, because the envelopes account for more of the wait than the signing ever does.
The Cardiff → Myanmar route step by step
Start by choosing the sheet that will travel. Cardiff Register Office at City Hall, Cathays Park, Cardiff CF10 3ND prints fresh certified copies of the city's birth, marriage and death entries, and a copy is what belongs in the post. The record sitting in your own file is the harder one to replace, so it should stay where it is.
Papers carrying a private signature take a different opening: notarisation gives the FCDO a signature it already holds a specimen of. From there the file goes to Milton Keynes, comes back certified, and only then goes on to the mission acting for Myanmar. Three desks, several journeys, and one package worth tracking at every stage.
Cost & timing for this route
Only one number on this route is knowable in advance. The FCDO charges around £45 for its certificate; the consular fee is set on the Myanmar side and added afterwards. Anyone pricing document legalization for Myanmar should treat the British figure as a floor rather than a total, and keep tracked postage inside the same budget.
Language and the far end
Distance shapes this corridor more than paperwork does. Burmese uses a script of its own, so a Yangon reader may want a Burmese text beside the English wording, prepared as its own job and bundled with the file. Searches for embassy legalization for Myanmar from Cardiff usually come from someone with a date already fixed at the far end, and that date is what should drive the whole plan.