Update:
Today I had my phone interview with FBU to apply for SS. The agent couldn’t have been nicer, and it was very straight forward. I have some paperwork to do, but was assured it will be no problem and that my NI voluntary contributions will be calculated to bring down the WEP. My U.K. husband was interviewed too. He’s never lived or worked in the US but she assured us he was entitled to receive benefits just by being married to me. He does have to go to the embassy to get a SS number though, which I’m not too thrilled about. My husband is currently ill and unable to travel so his application is suspended but she said if he remains ill for a long time, they would send someone up to us to assign the SS number..
What a pleasant surprise!