NI and UC/ESA

Hi
Firstly, please allow me to apologise for not always issuing my gratitude for a given response on the forum. I become quite unwell without prior notice or warning and I can be unable to correspond for short periods of time. It is certainly not intentional.
I have what is quite an intriguing question. At one of the therapy groups I attend, there is a lady who was self employed before she became unwell. She was advised by her Accountant a number of years back, that she needn't continue making NI contributions as she had paid enough for her State Pension. This lady is now 60 and has not paid NI contributions for at least 5-6 years. She now wants to apply for ESA via UC, but she has not paid enough contributions in the two preceding years. She won't receive Income Based UC/ESA as it will be pointless given that her Husband receiver's Carer's Allowance for her at this time. If she does get it, then we believe he will forfeit his Carer's Allowance or she won't receive UC/ESA (one of the two I think, although I may well be wrong).
She has asked me if she went and paid the last two years NO Contributions, would she then be able to apply for ESA/UC Contribution Based Allowance? I understand this is only paid for twelve months (unless that has changed), but if she were to be placed in the Support Group it would continue. I think the crux of her question is whether a lump sum back payment of the last two years would be accepted, and if so, where on Earth would she pay it? Finally, given that the tax years run from April to March, would she be better placed paying the two years money (if acceptable), in April 2025?
Quite a meaty query.
Thank You in advance - Hughie

Thank you. Genuinely appreciated. Hughie.