I have been living abroad for over 3 years, and I contacted all the online banks (Rabo , Bank of Scotland, Northern Rock etc etc) about opening an account with them, and they all stated that I needed to be a tax resident to open the account. Proving you're a tax resident is done by providing them with the documentation that you have mentioned above. unless you have that, you're struggling unfortunately.
I cashed in my SSIA early, due to residency issues, and transferred my money over to my australian bank account, so that i could put it into an online demand account over here, rates of 5.5%-6%.
I know I will lose some money on currency conversions, but the interest earned in the meantime will hopefully outweigh that considerably.
Perhaps there are online demand accounts in whatever country you are currently resident in, which offer good rates of return, which you consider transferring your SSIA money into .