Good on you for giving this a go.
Just as a thought when you are looking at expenses etc

Double your expense amount and halve your income amount and you will be closer to reality.

Stuff always comes up, and people sometimes don't / won't / can't pay.

Another string to the bow of this service you might want to think about, particularly for the elderly is just popping in for a coffee, and check that they are ok.

We've had several instances of people dying in a flat and not being found by the council for weeks. Many old people are afraid of that sort of thing. So a service, along with running errands, that checks up on them, gives them a bit of human contact, on a regular basis, might be something else you could offer.

Just thinking out loud........