@designer_phil, how exciting for you and your girlfriend to have found something right away! @itexpert7 's sane advice aside for the moment, unless someone has a personal contact who owes a favor, :-), finding a lawyer who will be ready and able to get to work at the drop of a hat may not be feasible. Just some thoughts: Is it necessary to complete the contract tomorrow? Can you arrange for a few days to review it? It is also possible to work long-distance through a power of attorney, so you don't have to sign on the dotted line before you go, if you have only a few days in Portugal.
Lawyers' schedules are generally booked far in advance, and multiple steps may be involved to retain a good lawyer, such as an initial consultation to see if they first fit your needs (and your case fits their expertise), and then a contract or other documentation to ensure both you and the attorneys are clear on the expected services and corresponding prices, may/will be needed up front.
Even in the US, and even in a small town, getting a lawyer for a next day project is not common! (At least, that's my experience in growing up in a family of lawyers with both big-city and very small town offices.)
It does appear that it's possible to set up a situation in *advance* of a trip so that an attorney can be ready to complete a contract quickly -- presentations by attorneys you can find in Expats Portugal's business directory have spoken of this. Maybe a call to them could locate someone whom they might know? Perhaps a so-called buyer's agent is another alternative for more rapid assistance? (@Gerry of Expats Portugal may have ideas here.)
@designer_phil, you may have/likely have thought of all of this; please don't take offense if so, and you were just hoping to luck into some help! As a fellow person who has similarly found quickly a place they wanted, but did not follow @itexpert7 's sage advice 🙂 , I just wanted to offer you what I could, based also on my little sliver of experience when also looking quickly for an attorney. The buying process I thought would take a few days, based on sellers who were also pressing for a quick sale, has instead taken +6 months, and as painstaking as it has been at times, the service of good attorneys has been instrumental to avoiding huge pitfalls, given the significant differences in the laws and nature of real estate in Portugal versus the U.S., not to mention status as a noncitizen.