How to register for Vote (electoral roll)

Hi everyone,

After receiving my First British passport recently, I went to register myself to vote,

however, now they need our national insurance number,

so my British passport is on my maiden name as well as foreign passport, as you know its almost impossible to get it on Married name.

and my national insurance is on my married name as well as many other documents, which I ve adopted in many years of marriage

now they sent me a letter asking to provide more proof if I am to be put on register,
so what should I do? register on married name but passport is on maiden name,

I do have a marriage certificate, what do you think?

Moved question to Settling In forum.

You should have all documents of the same name. I suggest you register to vote in your British passport name.