heyy i use that EXACT same method. heres the deal, your temporary card that you got in the packet is only valid in the US, but when you get your permanent card in the mail after about 7 days from the time you opened the account... you can use it to buy from the UK. I do it all the time, but use up all the money because every 30 days the green dot card charges you 5.95.
(edit:btw last month on attitudes promo, i order like $80 in seeds and they told me the order never went through and to place another order. literally a few hours after paying for the new order they "somehow found" the money from the first order and they charged my card twice. this is the 10 or so time ordering from them and after they told me id get a refund... they stopped answering my emails and they keep telling me that i need to talk to rachel... yet shes never available when i call and she never calls me back. be very careful because im not the first person they did this to. and those prepaid cards dont give a shit and tell you tough luck. ill never order from attitude again, but the prepaid card works. and IMHO id order from castle marijuana seeds, they have the best prices and cheapest shipping but thats my opinion after being royally screwed from attitude for 2 months in a row now. now i make my own seeds but youll be good to go on your prepaid card after you get your permanent one...
but if youre looking for seeds, since attitude screwed me and charged me for 2 orders i now have an extra order coming with all march promos seeds plus 2 UFO's. i ordered greenhouse seeds super bud 5 pack and pure kush 5 pack all fem with the promo like i said. if you want any of them and dont want to wait for your perm card send me a private message)