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!]
Also the coverage in this area is better than Orange. But your mileage will vary.
If I had to come up with a moan about GiffGaff, my only one would be that they send too many SMS notifications that I wish I could disable (i.e. they send me three each month as my package expires and then auto renews).
Orange sent me even more annoying SMS about things like "magic numbers" and other nonsense. So GiffGaff aren't terrible even in that area.
I've never dealt directly with their CS. Everything is online. So I cannot comment on how good they are when things go wrong.