One of the problems is that in order to retire in anything approaching comfort, you have to start saving early into a private pension.
So, let's imagine that you start working at 21 and retire at 65. (For ease, 45 years.)
If you begin saving when you begin to work, just at £50 a month, and then increase your contributions 10% a year and put it into a decent plan that returns 8% a year, you'll retire with a £1.3 million pension pot, or about £66k clear without touching the principal.
If you start at 40 at £50/month, and do the same thing, you'll save just over £129k.
Even if you start with a higher contribution, it won't help as much: if you start saving at 40 at £200 a month, and do the same thing, you'll retire with a pension plan of £516k, or just shy of £26k not touching principal.
All of which is to say, starting to save for retirement early makes absolutely all the difference, assuming the world hasn't, you know, totally collapsed into chaos. It's never too late to start, but retirement savings in your 20s really, really matter if you're going to try to retire as early as 65.
I wish this was drummed into heads in school. It's really not sexy, and there are so many loans out there, but even a little savings now can have such huge dividends down the line.
(Obviously, this whole thing is an enormous shame and terrifying for those who can't put £50 away and part of the larger unfair system, but. Still.)