Apologies. I meant the Lebara sim cards are available online, from Phones4u, larger Asda stores (£2.99) and a few other shops. Also worth a look are www.lycamobile.co.uk . If you are lucky enough to have a good corner shop nearby, they might have both types of sim cards for 99p each.
There's not much to choose between the Lebara and Lyca sim cards. Both are "free" online when you buy £5 of credit. Both offer very similar international rates. Both give free calls & texts to other numbers that are using the same type of sim card (up to 10 minutes for Lyca, 15 minutes for Lebara). One difference is that Lebara currently charge 10p/10p/10p/10p for UK landlines/other UK mobiles/UK texts/0845,0800,0870 numbers while Lyca currently charge 5p/10p/9p/25p.
Both sims will work in any unlocked phones. The Lebara cards will also work in any phone that is locked to the Vodafone UK network and the Lyca cards will work with phones locked to the Orange UK network (or so I believe - please confirm or correct me if I'm wrong on anything).
The wife and a few of her friends natter away on Lebara sim cards but I reckon that I'll be switching my Asda sim (8p/8p/4p/? via the Vodafone network) for a Lyca one so that she doesn't natter too much to me and to get the 5p landline rate. I only found out about the Lyca cards today - anyone know of anything else that competes with these?