Borrowed instructions are the main time sink
Most of the wasted effort on this route comes from good advice about somewhere else. A neighbour posts a paper off, one certificate comes back, and the errand is finished inside a fortnight. That story is perfectly true and completely useless here, because it belongs to a country that reads apostilles, and Ghana has not joined that arrangement.
What Ghana asks for
Documents intended for Ghana require embassy legalisation, which puts the receiving country in charge of the sequence. A shared certificate exists precisely so nobody has to learn a second country's rules; without one, the rules that count are Ghana's own. Searches for what you need for an apostille for Ghana come from that same confusion, and the honest answer is a different route altogether.
Budget the time as if you had never done this
A consular route moves at the pace of the offices inside it, and there are more of them than a single certificate needs. None of that pace is set by how well you prepared, so build a fresh calendar rather than scaling one from a friend's fortnight. Order any certified copy you need from Sunderland Registration Service early, because that part really is under your control.
Why general guidance goes wrong here
Most published advice about British papers is written for the majority of destinations, which do read apostilles. It is accurate for them and misleading for Ghana. When a page, a form or an office template says one certificate finishes the job, read which destination it was written for before acting on it, because on this corridor it finishes nothing at all.