You don't say what you are going to do.
I have a 3gb contract with 3 for £8 a month. Reception is alright but 3 gb won't go far if you use iplayer etc. Perfectly adequate for browsing, emails and so on. If it is just for emails and browsing have you checked any add ons for your mobile phone? Not perfect but if you just need it for a short while may well be the cheapest option.