The route has no single manager
Most people picture one desk that takes a paper in and hands a finished paper back. Document legalisation for United Arab Emirates does not work that way. One British authority vouches for a British signature. A separate consular authority then speaks for the receiving side. Each acts on its own terms, and neither is answerable to the other.
Where United Arab Emirates stands
United Arab Emirates has not joined the Hague Apostille Convention. That treaty is what lets one certificate stand alone abroad, so outside it the older chain still applies. There is no apostille issued in Reading for use in United Arab Emirates that closes a file by itself, however correct the paper underneath it may be.
What each half actually does
The British half is narrow on purpose. The Legalisation Office checks that the signature or seal on your sheet belongs to a British public officer it holds a specimen for. It says nothing about whether you are eligible for a job, a visa or a marriage. The consular half is what carries the paper into the receiving country's own system.
The charge you can see
The British stage is priced per document at £45 for the standard postal service, and that charge belongs to that office alone. It is not a fee for the whole road. Because it is per document and not per bundle, the length of your list drives the British half of the bill, so decide early which papers really have to go.
Closing the gap yourself
What you need for an apostille for United Arab Emirates is, in the end, not an apostille at all, and an apostille from the United Kingdom to United Arab Emirates would leave the job half done. Plan the second stage before the first one starts: know which papers go on, and keep them together as one file when they do.