ESA3 form

Hi I’ve just received an ESA3 form saying I may be entitled to ESA IR I was placed in the support group in 2012 on contributory ESA. I’m struggling with the questions though.
I live with my mum as a joint owner we paid the mortgage off over 6 years ago she was my CARER until she became terminally ill with cancer last year. We now care for one another best way we can.
I also receive a NHS pension it’s only a small amount but I’ve got my latest increase statement out to send in along with my initial letter from the pension service. I used to get SSP back in the 1980s when I was on sick before I was told I had to retire on health grounds. Do I put I received SSP in the 80s I can’t remember how much or is it just dating back to 2012 the date on the letter? & do I say I’m a joint home owner as it’s only asking from 2012. A friend has said send in gas bills electric bills bank statements etc but it doesn’t ask for those it only asks for proof of money & pension ? Thank you