As far as the Electoral Roll goes, I believe that is just registering to vote, which you can't do since you aren't a citizen. Unless I am wrong... hopefully not, since I'm not on the Electoral Roll! (oops, x-posted with kate_mate)
As far as mobile phones, you may need hubby to do this for you. I have been here for more than a year and signed jointly to DH's bank account - I tried to get a phone the other day and he ended up having to do it because they said I had insufficient credit. I don't know about getting a bank account, but some people have had an easier time with this than others. We added me to DH's checking and savings accounts straight away and sent off for my debit card.
You will probably want to get your DH to add you to things like council tax and utility bills so you can save those statements for your ILR visa.
I'd say the first priorities are registering with GP and dentist, then scheduling NI appointment. For that appointment, you only need proof of looking for employment, like a letter or email inviting you to an interview, rejection letter, registration with an agency, or even an email that just says "Thanks for submitting your application." As long as they can see you are looking for work, you can get an NI number.
Really, that is about all you need to get started in your life here, so I think you will be fine and shouldn't worry too much. As long as you get those things done within the first few weeks, then you are on the right track.
