@Petals23 You need to work out how much you spend now annually, doing a spread sheet and allowing for major purchases in the future like cars, a new boiler, major repairs to your home that may crop up.
Also it's not clear if you are single or expect any inheritance down the line.
We are almost at retirement stage- normal retirement age as we both actually enjoy working believe it or not- and we've spent the last year doing very careful calculations on what we need to live on in relative comfort. I can tell you it's far in excess of £16K pa and that's without new cars, or expensive holidays overseas etc.
What puzzles me is you say you are self-employed so surely this is the perfect opportunity for you to downsize your work? You could drop down to 4 days a week, then 3, then 2 and so on. That gives you a taste for retirement.
Many people dream about retirement but the thing that most people forget is that we all need some kind of intellectual stimulation. Or we ought to! Using your brain post-retirement is very good for mental and physical health.
There is also evidence that working longer maintains health.
I am almost mid 60s and although I now work p/t ( self employed) I intend to carry on doing a small amount of work as long as I can, so long as it gives me the time to do other things.
Furthermore, if you look after your health, and are lucky, you ought to still be fit at 80 and able to do stuff. Retiring at 55 is very young these days and you need to accept you will still have 25 years to fill having fun - but not necessarily the income to enjoy life if you retire too early. Nothing worse than penny pinching in old age.
Maybe you just don't enjoy your job?