One mark, and the file is finished here
An apostille is a slip confirming that a named official signed the sheet beneath it. Countries inside the shared treaty accept each other's slips instead of running a chain of embassy stamps. Both countries here sit inside that treaty, so a sheet marked in Milton Keynes is ready for a Fijian reader with nothing added afterwards.
The sheet that travels, and the one that stays
So the interesting decision is not the route but the paper. The certificate at home and a certified copy from the register office say precisely the same thing, and both carry an official signature at the foot. Only one of them can be replaced by walking into an office and paying a small fee, and that is the one that belongs in the envelope.
Distance sharpens the point. A file bound for the South Pacific spends far longer out of your hands than one crossing the Channel, and it often reaches a reader who files it away rather than posting it back. Where a paper is likely to be handed over and kept, sending a reprint instead of the only sheet you own is simply the sensible way round.
Papers the register office cannot reprint
Not every sheet has a reprint behind it. A register office holds birth, marriage and death entries and can print those again on request. A degree, a trade ticket or a set of company records comes from the body that issued it, and a fresh copy is obtained there rather than at the Civic Centre. Where none exists, the sheet you hold is the sheet that must go.
What it costs, and how far ahead to start
An apostille from United Kingdom to Fiji is priced on this side only, sheet by sheet, with no consular bill sitting behind it. That makes the money easy to total before you begin. The kind of paper makes no difference to the rate, so a one-page birth entry and a thick company file cost the same to mark.
Time is the looser half. The British stage is short and steady. The long stage is the journey itself, and that is the bit people forget when they count backwards from a date in Suva. Start the errand well before the deadline that prompted it, and the marking office will never be the reason you are late.