What you actually get at the end
People look up what you need for an apostille for Poland, and the honest answer is short. A paper carrying a British public signature, and one pass through a single office by post. What returns is a certificate confirming that the signature is real, printed, signed and joined to your paper. That pairing is the finished thing.
It says nothing about the wording inside your record. Nobody reads it for sense, and nobody rules on whether it suits the use you have in mind. That narrowness is why the route is quick: one office answers one question about one mark, and it holds its own record of British public signatures to answer it with.
Why Poland ends the route here
Poland has accepted this certificate since 2005, so document legalisation for Poland does not run through a consulate at all. An apostille issued in Birmingham for use in Poland is complete on the day it lands back with you, and nothing further is fixed to it. That agreement holds between states, so it does not shift from one Polish office to the next.
The practical effect lands on your calendar. One stage means one wait, so the date depends on the post and on how quickly the record underneath can be produced. An apostille from United Kingdom to Poland goes wrong far more often for a missing or unsigned paper than for anything to do with the certificate itself.
Printed certificate or electronic one
The Legalisation Office works by post, and UK e-Apostilles are also available. Those are two forms of one act. A printed certificate exists once and has to be looked after, since losing it means buying the act again. An electronic one is a file, so it can sit in several places at once and none of those copies wears out.
Neither form changes what the certificate says or what it is worth. Choose by how the result will be handled: a folder in an office wants a printed sheet, and a mailbox wants a file. It is worth settling early, because the form is part of what you order at the start rather than something added later.
Most of the work is the paper underneath
Because a single office closes the job, every interesting decision sits before it. Which record is going? Is it signed by a public officer? How many finished copies will people abroad keep? Those three answers set both the cost and the date, and not one of them depends on the form the certificate takes.
For civil records the plainest route is also the safest. Birmingham Register Office at Holliday Street, Birmingham B1 1TJ issues certified copies of birth, marriage and death entries, so a fresh copy can make the journey while your own stays put. Ordering those copies together keeps the charge easy to predict at £45 / document (standard postal); £40 / document next-day (registered businesses).