Why this country asks for something else
Ethiopia has not joined the Hague Apostille Convention. That one line decides the shape of everything below it: papers going there need embassy or consular legalisation instead, so the British certificate opens a run rather than closing it. No apostille issued in Bristol for use in Ethiopia will finish the job on its own, however much was paid for it or how quickly it came back.
£45 by post, £40 next-day, and the line between them
The Legalisation Office publishes two figures. Standard postal work is £45 / document. A next-day service runs at £40 / document and is open to registered businesses. Read the two lines together and the useful point is not the small gap in money — it is that the quicker one is defined by who is asking, not by how urgent the job feels to the person asking.
So for most private readers there is one price and one speed at this end, and knowing that early is worth real days. An apostille from United Kingdom to Ethiopia moves at the pace of the post either way. Hunting for a shortcut that was never open to you costs time out of the stage you genuinely cannot control.
Who does what, and in which order
The order is fixed and each body owns one act. Bristol Register Office at The Old Council House, Corn Street, Bristol BS1 1JG prints a certified copy of a birth, marriage or death entry. The FCDO Legalisation Office at PO Box 6255, Milton Keynes MK10 1XX then adds the British certificate by post. A consular desk closes the file afterwards.
Because the run is sequential, money leaves at the front and the answer arrives at the back. The British charge is met before anyone abroad has looked at anything at all. If something has to be put right after the last desk, the usual remedy is a fresh copy and a fresh British certificate, so the same outlay goes out a second time.