I think it depends where you live, whether you have housing costs and so on.
Unless there is to be a total overhaul of the tax and benefits systems, however, a means-tested universal pension (I assume that is what you are suggesting?) will never work. It would entirely remove the incentive to pay into an occupational or private pension if every pound over the universal one is clawed back and given to those who don't pay or who have spent their own savings. People would be better putting their money under the mattress, and everyone would claim the free pension, making it less affordable.
I really don't know what the answer is. Something has to be done to ensure that nobody is left cold and hungry in old age, and too many people earn too little to have enough left over to provide for the present, never mind the future. On the other hand, it is patently unfair that someone who spends as they go is given money when someone else on the same income saves and has their money used to pay for the first one. It's the Ant and the Grasshopper, isn't it?
I'll be accused of communism or something, but I think we should increase tax substantially and progressively, so that there is enough to ensure that everyone who pays in is given a decent pension on top of whatever they are able to save for themselves. I can't put a figure on that, sorry - something akin to the earnings of someone on minimum wage? Or should it be a bit less to be fair to those who are working? I also think that minimum wage should rise so that someone on a 40 hour week earns enough to live decently - not just scrape by, but have enough not to worry about food and bills, and be able to go to the pub, cinema, football, whatever now and then. It's not much to ask, is it?