Hi Scott,
To be honest it was really stressful before we left the uk as it was very rushed from this end also bearing in mind you have waited. Polaris had informed our solicitor that we needed to complete 3 weeks earlier than we planned to, we had a visit for a 2 week holiday which we had advised our solicitor of beforehand. We stuck our heels in and we went when we planned, dont be bullied, our view was we waited 3 years with very little contact if they want there money and cant wait 3 weeks its a poor situation, it all seemed very last minute. I was panicking about mortgage what was needed were Polaris going to get in touch was everything in place where to go what to do etc etc.
However saying that a good solicitor is a must - without ours I would of felt even more stressed. On the day we arrived for our 12 o'clock appointment, met our solicitor, she translated the documents checked all details with us, then we waited for the bank guys to arrive, Polaris people and the Notary. Bit dawnting lots of spainish (obvioulsy) lots of pointing everyone nodding to the right questions by the Notary. But all in all a very slick process, we were out with our deeds 2 and half hours.
As I say a good solicitor will take a lot of the weight and is a huge help, I cannot praise ours enough.
Yes definately hire a car.
Good luck