Best pre-paid sim cards for the UK, Spain and Portugal?

Hi! I am going to the UK, Spain and Portugal next month. Is there a universal prepaid sim card I could purchase overseas that will cover all these countries or would I have to purchase a sim card for each country?

The 3 SIM covers the UK & Spain, but not Portugal.  They're £15 pm in the UK or $40 from Simcorner, and they give you lots of data & text, unlimited data in the UK or 25 GB when roaming in other countries.

A $2 Globalgig Sim with a Go Europe + USA plan will get you data only (no calls included) coverage in those countries! $30 for 1GB or $50 for 3GB per month are great for your tablet - just remember to cancel your plan before the next billing period commences! Read the fine print carefully - they require your credit card details to sign up and the penalties for exceeding the data limits are steep! 

I have just used the sim in Croatia, Slovenia and a few other Euro countries and found it excellent! 

Globalgig sims are available at Harvey Norman and many other retail outlets. (Globalgig.com.au)