Start at the end of the road
An apostille issued in Brighton for use in Nigeria is not accepted, so the certificate most readers have in mind is not the last thing that happens here. The road ends with consular legalisation instead. Fixing that as the destination first is what keeps the rest of the plan honest, because every earlier step now has to justify itself by getting the file to that desk in a usable state.
Forward planning fails on routes like this for a simple reason. Each stage produces something that looks final — a sealed sheet, an official mark, a returned envelope — and it is easy to mistake any of them for the finish. Reading the route from its last line upwards removes that trap, because you already know what the last line says.
The stage that has to come before it
A foreign desk will not act on a British paper that carries nothing from the British side. So the stage immediately before the ending is the official certification of the sheet itself, handled by The Legalisation Office (Foreign, Commonwealth & Development Office). It works by post from PO Box 6255, Milton Keynes MK10 1XX, and there is no counter anywhere to shorten that exchange.
This is also where the arithmetic enters. The charge is per document rather than per envelope, so the number of separate papers you send multiplies the bill without lengthening the wait very much. Deciding the contents of the file at this point, rather than adding to it later, keeps both the cost and the number of postal journeys down.
And the sheet underneath all of it
Keep going back and you reach the paper the whole chain rests on. For civil records made in this district, Brighton & Hove Register Office at Town Hall, Bartholomew Square, Brighton BN1 1JA issues certified copies, and a copy of that kind is a full official record rather than a duplicate. Sending one keeps the sheet you already hold safely out of the post.
Because it sits at the bottom of the derived list, it is also the item with the longest lead time in effect. Nothing after it can start until it exists. So although a certified copy is the cheapest thing on the route, it is the one worth ordering first, and the one most likely to hold everything up if it is left until the plan feels urgent.
Turning the derived list into dates
Now reverse the list and give it a calendar. Copies ordered, then the British certification, then the consular ending, with a postal gap sitting between every pair. Knowing what you need for an apostille for Nigeria would not produce this schedule, because that certificate is not the ending here and a plan built around it stops one stage short of where the file has to get to.
Working backwards has one more benefit worth naming. It tells you what to do when a deadline is already close: not to hurry the desks, which do not respond to hurry, but to shorten your own part by deciding the contents of the file straight away. Document legalisation for Nigeria takes the time it takes, and the only slack in it is at your end.