Newbie ESA Questions

Hello all,
I have just joined and hoped somebody could answer a couple of questions for me please?
I have never made a claim before and know nothing about this.
Im planning on submitting an ESA claim (and then claiming the additional 'support group' element)
Where should I start?
Which guides should I read first?

Additionally, I contacted a disability charity about 18 months ago, in anticipation of making this claim, and they told me that I had to make a claim within two years of my last national insurance payment.
I have paid national insurance class 2 for 2018/19 and 2019/20 and all previous years, except 15/16, which was missed due to serious illness.
So I thought that I had until April 6th 2023 to make a claim, as that is the end of the tax year, but I rang up the ESA helpline yesterday, for the first time, for general advice, anonymously, and the person I spoke to told me that I only have until January 2023 to make a claim, because they operate from Jan to Jan, not Apr to Apr.
(Is this accurate?)
If so, presumably I will have to make this claim before the end of December 2022?

The person I spoke to on the ESA claim line also seemed to be saying to me that I have to have 'contributions' of at least £6.5k in each of those tax years to qualify for ESA?
I think she meant that I have to have paid myself at least £6.5k in both 2018/19 and 2019/20 in order to qualify?
Is that what she meant?

Thankyou.

There are two national insurance (NI) contribution conditions, both of which you must met be entitled to ’New Style’ ESA. The first condition depends on your NI contributions that you have actually paid the relevant tax year. (if you make your ESA claim in the 2022 benefit year, you need to have paid 26 weeks contributions in one of the following tax years: 2019/20 or 2020/2021) there are exceptions.

I became too sick to work in 2014. Bedbound. With a rare and incurable illness.
I didnt get to see a specialist in my disease for a number of years after that, and in 2018/19, the specialist, along with my other doctors, confirmed that I had in fact been fully incapacitated since 2014.
So I only received confirmation of my incapacity four or five years after I was incapacitated.
(In 2015 I rang the revenue and told them to 'shelve' my small business until I got better and went back to my sick bed.)
After the specialist confirmed my disability, in 2020 I contacted the revenue and informed them what had happened and out of my own savings I then back paid my national insurance for the missing years.

Test

Thankyou.
Does anyone know, what is the criteria, with which they decide upon whether or not you are entitled to income based ESA, or contribution based ESA?