Until it happens that is pie in the sky. Anything could happen. And it still isn't "her house, her money" - it is shared with her husband. He has some rights in this discussion too - perhaps he is tired of working too, perhaps he'd like to quit, and that £100k that isn't remotely banked yet is suddenly looking smaller.
The OP has also said "My out goings on house and energy/water/ council tax/ TV licence/ internet are £450 a month and my DH pays the same . I just pay for my own phone and life and car insurance on top of that" - so presumably she doesn't eat, buy clothes, have any entertainment or holidays, use cleaning products..... in other words, there is a hell of a lot more money being spent than she is accounting for. Either her husband buys everything else (in which case he may have something to say about paying for everything and then some), or she isn't being reotely realistic about her outgoings. She also may only have a small amount of time until the mortgage is paid off, but she also has on a small private pension - the state pension and a small pension aren't going to go far, and we have no idea what her husband will be relying on. It would be easy to burn through £100k (that doesn't yet exist) in what could be over 20 years more life. One big unexpected repair on the downsized property could easily eat through 25% or more of that money. And that is all assuming that they can sell the property and sell it for what she thinks it is currently worth.
Without a hell of a lot more certainty it would be foolish to rely on poor maths and guesswork to fund what could be many years into the future without falling into poverty just so one can quit without another job to go to. Making a mistake like this is reparable at 30, or even at 40, even if it leads to a few hard or lean years. Making the mistake at 60 means there is no time to repair it, no energy to do anything else, and could lead to the rest of one's lifetime in poverty.
I think the OP needs to be considerably better armed than a wing and a prayer before doing something like this. I am not saying don't make changes. Or even, don't do it. But it takes a hell of a lot more than "life's too short" from a bunch of anonymous posters. It takes proper planning and advice, and clarity about the future prospects. Without that you may find that no matter how short life is, it feels a lot longer than you thought possible. Poverty does that to people.