Sim card plans for Spain (particularly Barcelona)

We just visited Spain in October & I purchased a SIM card in a 'Telecor' Phone Store in Madrid.

I know you won't be in Madrid, but you can go to any phone store & select the SIM card that best suits your needs.

The main phone service providers are Movistar, Vodafone, Orange, Yoigo... & Lebara.

The salesman at Telecor recommended a SIM card by Lebara which was a great deal for me.

You can read about their phone plans & SIM cards here to get an idea: http://www.lebara.es/
You can change the website to English by clicking on the small white arrow on the top left.

Here is the address of a Telecor Store in Cadíz:

Av. de Andalucía, 34, 11008 Cádiz, Spain
+34 956 26 10 27

You can also check google maps for other cell phone stores.

Hope this helps!

Stick to what youth does over here: go for a low-cost well established brand (most of which are second-brands from the major players). Lebara is not, so I'd stay away from it. Among other, you might want to have a look at these:

https://www.tuenti.com/
https://www.lowi.es/
http://www.yoigo.com/
http://www.simyo.es/
http://www.pepephone.com/

However, my best advice would be to go to a shop upon your arrival and ask there since there's a 'fare war' going on at this moment (and it's likely to go on for a while) and each company is making ever more attractive offers to try to lure customers. Besides, as telecomms have been doing for a while (at least here in Europe) offers are often confusing and difficult to compare among companies.

You need a "tarjeta SIM sin contrato" (pay as you go). Also notice that it's a bad idea to use a SIM from one country in another country because you incur into expensive roaming charges, I'm mentioning this because if you get a SIM card in Portugal I wouldn't use it in Spain (and vice versa), I would get one for each country instead. The EU Commission has announced a plan to abolish roaming costs among the 28 EU countries to be in place in 2-3 years... but we're not there yet.

IMPORTANT: I do assume your phone is unlocked since you mention using it already in the UK, isn't it? For other readers that might be interested in such arrangements: many phones --especially those provided by your telecomms company back home and that are under 'special' plans/discounts-- are likely to be locked, that is, you can only use it with a SIM card from your provider. In order to use a different SIM card you need to ask your provider to "unlock" your phone. They do it remotely over the phone. And you have to do BEFORE you travel! :))

Thanks for the recommendations.

To add a few notes:
1) Yes, my phone is unlocked. As you point out, you need to make sure it is (or can be) or you are stuck with your home carrier. Not everyone knows this.

2) Your point about roaming charges is quite valid and I was not intending to purchase a sim card/package until we reached a stop in Spain.

Good to point these things out to someone who may find this thread later on.
Thank you again for your help.

Pleasure :))