I am sure if you spoke to your local library they will have a list of organisations you could contact.
A lot of older people, including pensioners and those who have never really worked with computers during their working life, are really desperate for some "one to one" help in talking them through the basics of getting started with a computer, especially understanding e-mail and using the internet. If you put up a card in a local newsagent I'm sure it wouldn't be long before you were getting requests for help. I think you're doing something really worthwhile and I hope you get a lot of satisfaction from it.