I suggest you pay off your mortgage ASAP then start investing/saving your old mortgage payment . Meanwhile, think of ways to reduce your spending requirements for life :
Live in a home that's well constructed, easy to maintain,. cheap to heat. Close to public transport to services you'll always need (supermarket, library, GP).
Learn to grow food, cook, make stuff, upcycle, mend stuff, DIY skills. Develop affordable/free hobbies and social interests (playing music, walking/running/cycling/reading/ singing/sewing/gardening. Acquire saleable skills that are always in demand (reiki, childcare, crafts, computer buddy, translation; think wide).
List everything you spend and buy so that you can see ways to eliminate waste and live more economically and sustainably. Look after your teeth and health.
List the unavoidable expenses; CT, food bills, and the stuff you could live without ; car, takeaways, beauty treatments and products.
A few years of doing that and A) you'll know exactly what part-time work income you could live on in reasonable comfort and B) what you need to salt away as a contingency fund. Consider a period of middle age "lean and mean years" on a very reduced income between stopping full time work, and the start of pensions.
Its all about longterm planning. But a lot of financial planning, is less about money-investment and more about skilful creation and management of longterm personal resources.