Embassy legalisation for use in Peru
Peru accepts a single-step certification, so the consular part of the usual chain is absent from this corridor and there is no embassy attestation for Peru to arrange. Your certified copy needs one certificate from the FCDO Legalisation Office and is then complete. Saying that early matters, because half the cost people expect on a route like this sits in the stage that has been removed. Plan for one office, one fee and one wait.
Where the money actually goes
An official fee applies at the Legalisation Office and that is the only public charge on the route. Alongside it sit two private costs you arrange yourself: the fee the register charges for a fresh certified copy, and postage both ways. Consular legalization for Peru would have added a third charge at a consulate, along with its own opening hours. None of that reaches your file, so the budget is short and easy to check.
The Belfast to Peru route in one stage
You order the certified copy, post it to Milton Keynes, and wait for the certificate to come back bound to the paper. Standard handling is 7–10 business days once the office opens the file, and the express route closes in 2–3 business days for people working to a deadline. Nothing sits in a diplomatic queue afterwards. Because embassy legalization for Peru from Belfast is not part of the picture, no foreign holiday or closed consulate can stretch the timetable.
Building the calendar backwards
Start from the date the paper is due in Peru and count back. Give the office its 7–10 business days, add several days of post in each direction, then leave a week at the front for the register to produce the certified copy. That arithmetic usually lands three to four weeks before the deadline, which is comfortable. The express route buys back about a week when a job slips, and it is the only lever that shortens the official side.