Dottilind, When I was working for Age Concern (as was), I was visiting elderly people at home, advising on state benefits and any other problems they had. I even represented some clients at Social Security Tribunals. Not work that school leavers or even new graduates could do. Most of the Home Advisors were retired people and very elderly people felt more comfortable with us, particularly when they were having to admit to embarrassing medical problems like incontinence or having to give us details of all their financial circumstances.
My local Age Concern also had a local telephone befriending service and a number of other volunteer roles that older people did. It is also worth visiting your local volunteering centre. Another very small charity I am involved with managed to find some one with book keeping skills to be our treasurer through the Volunteer Centre and I currently volunteer for a heritage charity, an opportunity which I found on the volunteer website run by my local county council. There are plenty of volunteering jobs out there that cannot be done by school leavers where more mature volunteers are welcome.