Once you have signed your deed poll, you should never send your original away. Instead, you make certified copies — photocopies that you have signed and annotated to confirm their authenticity. A certified copy carries the same evidential value as the original for the purpose of notifying organisations of your name change, and most organisations (including the Passport Office, DVLA, and banks) will accept them without question.
Making a certified copy is simple: photocopy your signed original deed poll, then on the copy write by hand "I certify this to be a true copy of the original deed poll" and add your new name signature and the date. That annotation, written by you on the copy, is what makes it "certified". Some organisations may also ask you to sign it in both your old name and your new name — it is good practice to do this on every certified copy in case it is required.
There is no limit to how many certified copies you can make. You should make enough for every organisation you need to notify, plus a few spares. Keep your original signed deed poll somewhere safe — a folder at home, alongside your other important documents. You should not need to produce the original again unless a specific organisation requests it, which is rare.