A word of caution: a lot of that depends whether you’ve been officially medically retired, and thus able to start drawing your pension immediately, or have simply made the decision to stop working.
In the latter case, there are good reasons still to contribute to a private pension, if circumstances permit, as you can contribute up to £2880 net each year, even if you’re not earning, on which the government will give you basic rate tax relief, to round it back up to £3600!
I’ve made a point of maintaining my pension contributions since finishing work - especially since the introduction of the new pensions freedoms - which mean I’ll be able to do as I like with it from 55, and not be forced into an unfavourable annuity.
It’s a lot of money when I’m living on savings and investments (no salary or benefits), but not doing so would mean I was writing off £720 in free money from the government each year, so it’s worth tightening my belt now, to get more back when I can eventually access it in a few years.
Similarly with NI. Naturally, if you’re no longer working, you’re not obliged to pay it. But if you’re short of the number of years necessary to guarantee a full state pension (I think currently still 30, but will be moving to 35 imminently), you can elect to make voluntary contributions in years you’ve stopped working, to secure your entitlement.
I have not yet decided whether to do this, as I won’t qualify for my state pension 'til I’m 67 at the earliest, and I expect it to go back still further before I get there, so it may well be 70+.
I currently have 29 years’ contributions (should be 31, but I have two years missing from when a former employer deducted them but didn’t forward them, and it’s too late to correct now).
I have to weigh up the expense of making the voluntary top-ups with the risk I may not live to see my state pension age - which keeps rising - and thus it will have been money wasted. Unfortunately, voluntary NI contributions ONLY count towards state pension. You can’t use them to access other contributory benefits, such as contributory ESA or JSA.
I’m just pointing out that stopping work needn’t automatically mean an end to pension contributions or NI. Depending on individual circumstances, there might be a case for still doing one or both, voluntarily.