Which route applies for Zimbabwe
An apostille is one certificate that Convention countries agree to take from each other with no further step. Zimbabwe has not joined the Hague Apostille Convention, so that route stays closed. Papers going there need document legalisation for Zimbabwe: the UK certificate first, then a consular stamp added by the desk acting for the country. Both marks have to be present when the sheet is finally handed over.
Plan around what you can observe
The chain gives you no progress reports at all. Nobody writes to say a file has reached the top of a pile, and nobody warns you that a pile has grown. What you get instead is a small number of hard events: a copy collected, an envelope delivered, an envelope returned. Building a plan on those, rather than on estimates, is the difference between waiting and drifting.
An apostille issued in Newcastle upon Tyne for use in Zimbabwe produces one of those events cleanly, because the sheet comes back to you before the consular stage begins. That return is worth treating as a milestone. Date it, and you have measured one third of the route with real numbers instead of hope.
The Newcastle upon Tyne stages
Newcastle Register Office, at Civic Centre, Barras Bridge, Newcastle upon Tyne NE1 8QH, re-issues civil records as certified copies, so the certificate you keep at home stays out of the postal system entirely. A court paper, a college paper or a company paper starts with the body whose signature sits at the foot of it, and that body sets its own pace for reprints.
The sheet then travels to the FCDO Legalisation Office, PO Box 6255, Milton Keynes MK10 1XX, which handles the whole country by post. What you need for an apostille for Zimbabwe here is a recognised signature and an unaltered page. Send it tracked, and note the delivery date, because that is the last hard fact you will hold for a while.
Cost and timing on this route
The UK stage has a fixed price: £45 per document by standard post, or £40 per document on the next-day service open to registered businesses. An apostille from the United Kingdom to Zimbabwe then meets the consular charge, which the mission applying the closing stamp sets for itself. Because two of the three waits are unpublished, margin in your own timetable does the work that a tracking page cannot.