well you can get the 3sim for free from the 3uk store. Top up the £10 online like I said and then try it for a month. In some places its not good but if it works in the areas you travel you cant beat it. If its no good o2 simplicity would be my next and only choice.

I live in Croydon which is a main town, I use voda, o2 and 3 mifi. Vodafone is disgusting and im glad I only got a 12 month contract. o2 never fails me and 3 is sometimes patchy but the speeds really are the best.