The route Nepal uses
Nepal has not joined the Hague Apostille Convention, so an apostille for Nepal is not the certificate its offices act on. Papers travelling there require embassy legalisation instead, through a chain of desks. Settle that and the rest of the work becomes practical rather than legal, and the most practical skill of all is being able to say exactly which piece of paper you want.
The four things that identify a paper
Any document can be pinned down by four facts: the body that issued it, the event or entry it records, the names as written on it, and the date. Give an office those four and it can find your record in minutes. Leave one out and the search widens, the answer slows, and you end up trading messages across time zones about a detail you already had in a drawer.
Titles travel badly, purposes do not
A request written in Nepal will use its own vocabulary, and forcing that wording onto a British office rarely helps. Ask instead what the paper has to prove, then find the British body that proves it. Readers looking up what you need for an apostille for Nepal usually have a list of unfamiliar titles in front of them, and translating each one into a purpose is what turns that list into something you can act on.
Asking the right office
Newcastle Register Office can issue a certified copy of any birth, marriage or death registered in the city, and that copy is the sheet that should travel while your own certificate stays at home. Nothing outside the civil registers is its business. Document legalisation for Nepal often stalls simply because somebody asked a register office for a document it was never going to hold.
Reading the sheet before it moves
When the copy arrives, read it against your notes line by line. An apostille issued in Newcastle upon Tyne for use in Nepal would be attached to whatever sheet you supplied, right or wrong, and so will every mark on the embassy route. An apostille from United Kingdom to Nepal would not correct a misspelling either. Errors are cheap to fix before the file moves and expensive afterwards.