The missing link: Portugual

If you google bus and train transport in Portugal you will the main websites for bus and train times and tickets. You can get both a bus or train to both Lisbon and Coimbra.

Porto and Coimbra damn no edit

Hey!

Staying at least 4 days in Lisbon is really worth it, and considering it´s August, I'd strongly recommend heading south as well if you have time (costa vicentina in Alentejo, and Algarve for fantastic beaches). After that, for going north, you can take a train (www.cp.pt) or the bus straight from Algarve, Lisbon, Coimbra, or pretty much anywhere. The biggest companies are Rede Expressos and RENEX. For Algarve connections, you have EVA. There's normally no need to book in advance, but you can check the schedules online.

Yes, Coimbra is a beautiful student town, I'd sleep there for one night to visit the best places. In the way to Porto, of have of course some worthwhile places but probably the best would be either to stop in Aveiro (and see the coast - Costa Nova, Ílhavo), or to go straight to Porto and stay there for 2 or 3 days. From Porto to San Sebastian in 2/3 days, well that would be tough. I'd allow at least one week - the better route to follow is Porto- Viana do Castelo (beautiful place with many beaches in the surroundings)- Vigo - Santiago de Compostela (mandatory stop if you're a christian) - Oviedo (beautiful city) - Santander (good stopover for beaches) - Bilbao (very much worthwhile) - San Sebastian. You have spanish trains and buses connecting all these cities. If you want you can also go straight to Porto to Vigo by direct train.

Any question, just ask (I´m from Porto.)
Maria

Coimbra is definitely worth a visit.

It is one of the oldest Universities in Europe with roots dating back to the 1200's.

The student life melds with the fabric of the city

Its location on the Mondego River has been historically critical and there have been settlements there or near there since roman time.

For some more info have a look at this recent article:

http://barlaventostravelblog.blogspot.pt/2013/01/coimbra-portugal.html

There are plenty of low-cost pensions in Coimbra.

There is also a "Pousada de Juventude", state youth hostel.

See also: http://www.turismodecoimbra.pt/index.php?lang=en

As regards travelling to San Sebastian/Donastia from Porto you basically have two routes:

1) Through Galicia via Vigo, Santiago da Compostela, La Coruna, Oviedo, Santander and Bilbao.

2) Via Salamanca, Valladolid, Burgos, Vitoria, and Bilbao.

This can all be done by long distance coach (See: alsa.es) or train. (See renfe.es / www.cp.pt)

On both routes, there are historic cities worth visiting. In Bilbao you also have the Guggenheim.

There are other cities in the region like Zamora, Ourense, and Leon among others that might interest you.

Basically you need to have a look at the articles on these cities on wikipedia. Decide which ones interest you and then plan your itinerary from there.

There's a direct overnight train from Coimbra-B to San Sebastián that could be a good option for you.
If you want to make the route from Porto to San Sebastián in stages stopping at some locations in Spain, there are several options but it would be necessary to know what are your interests, what are you looking for (e.g.: Art? Nightlife? Shopping?...) and how many time do you really have (as it's not the same 2 than 3 days).

Thankyou all so much for your input, it's been so helpful!

I've got a few different options now which is great :) we'll just see how far my budget can stretch!