Earlier quoted context omitted.
And then join up with who? All of the 3G operators have similar opt-out filters. Orange makes you give them your credit card number. GiffGaff made me give them my drivers licence number. I like that with GiffGaff I didn't need to talk to a person, just do it online, but in general you'll have to deal with this no matter who you sign up with. I think even Imgur (Reddit's image host) was blocked at one stage.
Out of interest, how are you finding GiffGaff - £12 for a plan with unlimited internet and texts and no contract looks too good to be true! [Edit: thanks to everyone who has replied, I think I will give them a go!]
When I was buying my phone, I realized how much money I could save going with them. I could either go with a 24 month contract for 35 pounds per month and get the phone "free", on a contract which included 500mb of data, 1000 minutes and 1000 texts - spending 840 pounds in total, or just buy the phone outright for 500 pounds and go with giff gaff, spending 740 pounds over the course of 24 months, saving myself a nice 100 pounds and getting a better deal.