Returning resident

I'm a US citizen but returned to the UK when I was 6.  I moved to the US in April 2004 but until this year I didn't have a US SS number and only worked in the UK. MY questions are:-
I will only have earned less than $1000 when I return to the UK, will I have to file all future UK earnings now that I'm in the system over here?
Will my husband on getting a Spouse Visa have to declare UK earnings?
This is a minefield that I never thought about until I started to read the posts..sometimes ignorance is bliss!