Obtaining Foreign Currency for Gibraltar

There are booths where you can exchange currency at the parking lots before you cross into Gibraltar. I have no idea if the exchange rates are terrible but as we only did a few hours, it was very convenient to exchange money before we walked across - then exchange it back as we were headed back to our car.

Gibraltar pounds are just a variant of British pounds, not a separate currency.
But, I wouldn't bother. Just get some from a bank cash machine when you arrive, or I guess most tourist places take Euros.

Although the currency value is pounds sterling, do be aware that exchanging Government of Gibraltar banknotes outside of Gibraltar is not always straightforward - especially in Spain away from the border area.

Euros are accepted at a generally poor rate. You may be able to get along with cards only depending on what you are doing.

Also if you happen to have Bank of England notes they are spendable in Gibraltar at face value and don't need exchanging.

Just don't hold them up or you will get pickpocketed by the apes.

And don't wear a hat.

If you get sterling in advance, get small bills, or spend it all. If you get change in Gibraltar notes, they'll be useless anywhere else. The coins are the English ones.