Hi
These are 2 cards that you can get very easy.
http://www.1-mobile.be/SP_Abroad.cfm?lang=nl
Starterskit: €15, includes €6 callcredit
UK is in zone 1; €0,29/min fixed; €0,49/min mobiles
http://http://www.aldi.be/ALDI_BN/TALK_BN/index.htm
Starterskit: €15, includes €10 callcredit;
does not publish international rates.
If you need some help in finding these supermarkets, just mail me (no PM please). My email address is my ppgsm account at gmail.com
Yves