Can someone please tell me the best way to get to Cordoba from Seville and whether you need to book ahead the main sites there? Also I don't seem to be able to access the Renfe site on my computer - any tips would be helpful. Thanks in advance.

A number of trains a day ..AVE( fast train) takes 45 min.
www.renfe.com

No need to book sites ahead of time.

I hate to disagree, but booking ahead saves a lot of valuable time. If you are from the States or Canada, you can buy your tickets at Petrabax.com, but the Renfe site shouldn't be a problem, we use it quite often.

We bought our train tickets to Córdoba the day of our departure and it took about 5-10 minutes. We waited because we wanted some flexibility. Unlike some routes, we also didn't find discounted advance purchase fares.

We didn't perceive a need to buy tickets in advance for Cordoba's main sights.

There is also the option of bus. Renfe is particular about computer platform. Try IE, Chrome,or Firefox. If a Apple, not sure of your options, but change whatever you are using.loco2 is an alternative reputible purchasing website for train tickets.

I was saying that booking sites, like Mezquita , ahead of time was not necessary.
Booking on Renfe with a Canadin CC was never a problem for us.

And maybe a lunch in Taberna Salinas? Many fine traditional tabernas just north of the Mezquita and close to the Roman temple ruins: http://www.tabernasalinas.com/en/

Many fine and local atmosphere places to choose from in this part of town: http://www.cordoba24.info/tavernen/h...vernen_en.html

The temple ruins: http://www.spain.info/en/que-quieres...lo_romano.html

Taberna El Gallo, next door to the ruins, is as genuine as it gets. Also a few tables outside in the narrow street: http://azahar-spain.com/azahartapas/taberna-el-gallo/