Spanish is the language Mexico works in
Papers used in Mexico are read in Spanish, so a certified translation into Spanish in Newcastle upon Tyne is what makes an English record usable there. The rule takes no interest in what shape your record arrived in. A Spanish version is required for documents used in Mexico whether the source is a printed certificate or a file you have never once held.
The file is the record
A certified translation for Mexico is written from what you were actually issued. Where that is a file, the file is the record and the printout is a copy of it. So send the file. It carries the text at full sharpness, holds its pages in the order they were made, and brings none of the shadows, crops and folds that a photographed sheet arrives with.
Two habits that cost you a day
The first is photographing a screen, which blurs fine print and usually clips an edge. The second is sending only the pages that look interesting, when the file also holds a cover sheet, a footer and a block of reference numbers. All of it gets written out, so all of it has to arrive, and a missing page is discovered at the point where it is too late to be quick about it.
The certificate that goes with the Spanish
The Spanish comes with a certificate of accuracy from a certified translator: a name, a date, a signature written by hand, and a line naming the record the Spanish was made from. No court and no oath come into any of it. An official Spanish translation in Newcastle upon Tyne is backed by that single page and by the person whose name sits on it.
Per-page cost and turnaround
The rate is £25 for each page as issued, counted the same way whether the pages sit on paper or inside a file. Standard work takes 2–3 business days from the moment a readable copy arrives, and express takes 24 hours. A file sent exactly as it was issued usually raises no queries at all, which is the fastest version of this there is.