Why don't you consider a 3G pay as you go dongle to start with as discussed above.
I have to comment that as you are at Zambujeira, I suspect that even when you get your line in, broadband speeds will be at the bottom end of the advertised range. I am not sure where the local sub-exchange is, but I doubt that adsl speeds in that part of the Alentejo will not be great and if you are more than 2-3 kms from the local DSLAM, and dependent on overhead cables, expect climatic conditions to regularly impact on the line quality. Also, make sure your the electrics on property is properly earthed, keep a spare adsl router in the cupboard as lightning strikes and power cuts regularly fry these units.
I was called to a client a couple of years ago, situated between Lagos and Burgau. They needed broadband. Their phone line had a history of regularly frying fax machines owing to lightning strikes on overhead phone cables. I refused consequently to install Sapo over the landline because I could see what was going to happen, (i.e regularly fried modems/routers). I did however, rig them up a vodafone dongle on a yearly contract. I then attached this to a router and at one stage they had up to five machines running on it, although I would not normally recommend more than two or max three machines over such a system. I subsequently installed a similar system at Ingrina near Vila de Bispo where a property was to far from the exchange to install adsl over the landline.
The problem with a dongle solution will probably traffic volume as data transmission rates over the 3G network will be higher than over landline.